How To Draw The MandelBrot Set In Google Sheets, Using Only Formulas

How to draw the Mandelbrot Set in Google Shetes

This article will walk you through how to draw the MandelBrot set, using only formulas and the built-in chart tool.

What Is The MandelBrot Set?

The Mandelbrot set is group of special numbers with some astonishing properties.

You’ve almost certainly seen an image of the Mandelbrot set before.

It’s one of the most famous mathematical concepts, known outside of mathematical circles even. It’s named after the French mathematician, Benoit Mandelbrot, who was the father of fractal geometry.

The Mandelbrot set is fantastically beautiful. It’s an exquisite work of art, generated by a simple equation.

More formally, the Mandelbrot set is the set of complex numbers c, for which the equation z² + c does not diverge when iterated from z = 0.

Gosh, what does that mean?

Well, it’s easier if you look at the picture at the top of this article. The black area represents points that do not run away to infinity when you keep applying the equation z² + c.

Consider c = -1.

It repeats -1, 0, -1, 0, -1… forever, so it never escapes. It’s bounded so it belongs in the Mandelbrot set.

Now consider c = 1.

Starting with z = 0, the first iteration is 1.

The second iteration is 1² + 1 = 2.

The third iteration is 2² + 1 = 5.

The fourth iteration is 5² + 1 = 26.

And so on 26, 677, 458330, 210066388901, … It blows up!

It diverges to infinity, so it is not in the Mandelbrot set.

Before we can draw the Mandelbrot set, we need to think about complex numbers.

Imaginary And Complex Numbers

It’s impossible to draw the Mandelbrot set without a basic understanding of complex numbers.

If you’re new to complex numbers, have a read of this primer article first: Complex Numbers in Google Sheets

It explains what complex numbers are and how you use them in Google Sheets.

To recap, complex numbers are numbers in the form

a + bi

where i is the square root of -1.

We can plot them as coordinates on a 2-dimensional plane, where the real coefficient “a” is the x-axis and the imaginary coefficient “b” is on the y-axis.

Use A Scatter Plot To Draw The Mandelbrot Set

Taking each point on this 2-d plane in turn, we test it to see if it belongs to the Mandelbrot set. If it does belong, it gets one color. If it doesn’t belong, it gets a different color.

This scatter plot chart of colored points is an approximate view of the Mandelbrot set.

As we increase the number of points plotted and the number of iterations we get successively more detailed views of the Mandelbrot set. A point that may still be < 2 on iteration 3 may be clearly outside that boundary by iteration 5, 7 or 10. Mandelbrot set with more iterations and points

You can see the outline resembles the Mandelbrot set much more clearly at higher iterations.

How To Draw The MandelBrot Set In Google Sheets, Using Only Formulas

Here’s a simple approximation of the Mandelbrot set drawn in Google Sheets:

Simple Mandelbrot Set

Let’s run through the steps to create it.

It’s a scatter plot with 289 points (17 by 17 points).

Each point is colored to show whether it’s in the Mandlebrot set or not, after 3 iterations.

Black points represent complex numbers, which are just coordinates (a,b) remember, whose sizes are still less than or equal to 2 after 3 iterations. So we’re including them in our Mandelbrot set.

Light blue points represent complex numbers whose sizes have grown larger than 2 and are not in our Mandelbrot set. In other words, they’re diverging.

Three iterations is not very many, which is why this chart is a very crude approximation of the Mandelbrot set. Some of these black points will eventually diverge on higher iterations.

And obviously we need more points so we can fill in the gaps between the points and test those complex numbers.

But it’s a start.

Generating The Complex Number Coordinates

In column A, we need the sequence going from 0 to 2 and repeating { 0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 0, 0.25, 0.5, …}

In column B, we need the sequence 0, then 0.25, then 0.5 repeating 9 times each until we reach 2 { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0.25, 0.25, 0.25, …}

This gives us the combinations of x and y coordinates for our complex numbers c that we’ll test to see if they lie in the set or not.

It’s easier to see in the actual Sheet:

Mandelbrot set data

We keep going until we reach number 2 in column B. We have 324 rows of data. There are some repeated rows (like 0,0) but that doesn’t matter for now.

Columns A and B now contain the coordinates for our grid of complex numbers. Now we need to test each one to see if it belongs in the Mandelbrot set.

Formulas For The Mandelbrot Algorithm

We create the algorithm steps in columns C through J.

In cell C2, we create the complex number by combining the real and imaginary coefficients:

=COMPLEX(A2,B2)

Cell D2 contains the first iteration of the algorithm with z = 0, so the result is equal to C, the complex number in cell C2, hence:

=C2

The second iteration is in cell E2. The equation this time is z² + c, where z is the value in cell D2 and C is the value from C2:

=IMSUM(IMPOWER(D2,2),$C2)

It’s the same z² + c in F2, where z in this case is from E2 (the previous iteration):

=IMSUM(IMPOWER(E2,2),$C2)

Notice the “$” sign in front of the C in both formulas in columns E and F. This is to lock our formula back to the C value for our Mandelbrot equation.

In cell G2:

=IMABS(D2)

Drag this formula across cells H2 and I2 also.

In cell J2:

=IFERROR(IF(I2<=2,1,2),2)

Then leave a couple of blank columns, before putting the chart data in columns M, N and O, with the following formulas representing the x values and the two y series with different colors:

=A2

=IF(J2=1,B2,"")

=IF(J2=2,B2,"")

Thus, our dataset now looks like this (click to enlarge):

Mandelbrot dataset in Google Sheets

The final task is to drag that first row of formulas down to the bottom of the dataset, so that every row is filled in with the formulas (click to enlarge):

Mandelbrot dataset in Google Sheets

Ok, now we're ready to draw some pretty pictures!

Drawing The Mandelbrot Set In Google Sheets

Highlight columns M, N and O in your dataset.

Click Insert > Chart.

It'll open to a weird looking default Column Chart, so change that to a Scatter chart under Setup > Chart type.

Change the series colors if you want to make the Mandelbrot set black and the non-Mandelbrot set some other color. I chose light blue.

And finally, resize your chart into a square shape, using the black grab handles on the borders of the chart object.

Boom! There it is in all it's glory:

Simple Mandelbrot Set

Note: you may need to manually set the min and max values of the horizontal and vertical axes to be -2 and 2 respectively in the Customize menu of the chart editor.

How To Draw A Better MandelBrot Set in Google Sheets

Generating Data Automatically

Generating those x-y coordinates manually is extremely tedious and not really practical beyond the simple example above.

Thankfully you can use the awesome SEQUENCE function in Google Sheets to help you out. This formula will generate the x-y coordinates for a 33 by 33 grid, which gives a more filled in image than the simple example above.

=ArrayFormula(UNIQUE({
MOD(SEQUENCE(289,1,0,1),17)/8,
ROUNDDOWN(SEQUENCE(289,1,0,1)/17)/8;
-MOD(SEQUENCE(289,1,0,1),17)/8,
ROUNDDOWN(SEQUENCE(289,1,0,1)/17)/8;
MOD(SEQUENCE(289,1,0,1),17)/8,
-ROUNDDOWN(SEQUENCE(289,1,0,1)/17)/8;
-MOD(SEQUENCE(289,1,0,1),17)/8,
-ROUNDDOWN(SEQUENCE(289,1,0,1)/17)/8
}))

Then drag the other formulas down your rows to complete the dataset, in the same way we did above.

Then you can highlight columns M, N and O to draw your chart again.

Note: you may need to manually set the min and max values of the horizontal and vertical axes to be -2 and 2 respectively in the Customize menu of the chart editor.

With three iterations, the chart looks like:

Mandelbrot set in Google Sheets with 3 iterations

Increasing The Iterations

Let's look at 5 iterations and 10 iterations, and you'll see how much detail this adds.

To move from 3 iterations to 5, we need to add some columns to our Sheet and repeat the algorithm two more times.

So, insert two blank columns between F and G. Label the headings 4 and 5.

Drag the the formula in F2 across the new blank columns G and H (this is the z² + c equation as a Google Sheet formula):

In G2:

=IMSUM(IMPOWER(F2,2),$C2)

In H2:

=IMSUM(IMPOWER(G2,2),$C2)

We need to add the corresponding size calculation columns. Between K and L, insert two new blank columns and drag the IMABS formula across.

Now in L2:

=IMABS(G2)

And in M2:

=IMABS(H2)

Finally, update the IF statement in column to ensure it's testing the value in column M now:

=IFERROR(IF(M2<=2,1,2),2)

And that's it!

Our chart should update and look like this:

Mandelbrot set in Google Sheets with 3 iterations

You can see the shape of the Mandelbrot set much more clearly now.

Increasing from 5 iterations to 10 iterations is exactly the same. Add 5 blank columns and populate with the formulas again.

The resulting 10 iteration chart is better again:

10 iterations

Increasing The Number Of Data Points

Increasing the number of points to 6,561 in an 81 by 81 grid will give a more "complete" picture than the examples above.

This sequence formula will generate these datapoints:

=ArrayFormula(UNIQUE({
MOD(SEQUENCE(1681,1,0,1),41)/20,
ROUNDDOWN(SEQUENCE(1681,1,0,1)/41)/20;
-MOD(SEQUENCE(1681,1,0,1),41)/20,
ROUNDDOWN(SEQUENCE(1681,1,0,1)/41)/20;
MOD(SEQUENCE(1681,1,0,1),41)/20,
-ROUNDDOWN(SEQUENCE(1681,1,0,1)/41)/20;
-MOD(SEQUENCE(1681,1,0,1),41)/20,
-ROUNDDOWN(SEQUENCE(1681,1,0,1)/41)/20
}))

Be warned, as you increase the number of formulas in your Sheet and the number of points to plot in your scatter chart, your Sheet will start to slow down!

Adding Color Bands

We can add color bands to show which iteration a given point "escaped" towards infinity.

For example, all of the points that are larger than our threshold on iteration 5 get a different color than those that are less than the threshold at iteration 5, but become larger on iteration 6.

The formulas for the iterations and size are the same as the examples above.

Then I determine if the point is still in the Mandelbrot set:

=IF(ISERROR(AG2),"No",IF(AG2<=2,"Yes","No"))

And then what iteration it "escapes" to infinity, or beyond the threshold of 2 in this example:

=IF(AH2="Yes",0,MATCH(2,S2:AG2,1))

These formulas are shown in the Google Sheets template:

Next we create the series for the chart:

First, the Mandelbrot set:

=IF(AH2="Yes",B2,"")

Then series 1 to 15:

=IF($AI2=AK$1,$B2,"")

The range for the scatter plot is then:

A1:A6562,AJ1:AY6562

where column A is the x-axis values and columns AJ to AY are the y-axis series.

Drawing the scatter plot and adjusting the series colors results in a pretty picture (this is an 81 by 81 grid):

15 iterations with color bands

Reaching Google Sheets Practical Limit

As a final exercise, I increased the plot size to 40,401 representing a grid of 201 by 201 points. This really slowed the sheet down and took about half an hour to render the scatter plot, so not something I'd recommend.

The picture is very pretty though!

How to draw the Mandelbrot Set in Google Shetes

The 40,401 x-y coordinates can be generated with this array formula:

=ArrayFormula(UNIQUE({
MOD(SEQUENCE(10201,1,0,1),101)/50,
ROUNDDOWN(SEQUENCE(10201,1,0,1)/101)/50;
-MOD(SEQUENCE(10201,1,0,1),101)/50,
ROUNDDOWN(SEQUENCE(10201,1,0,1)/101)/50;
MOD(SEQUENCE(10201,1,0,1),101)/50,
-ROUNDDOWN(SEQUENCE(10201,1,0,1)/101)/50;
-MOD(SEQUENCE(10201,1,0,1),101)/50,
-ROUNDDOWN(SEQUENCE(10201,1,0,1)/101)/50
}))

Zooming In On The Mandelbrot Set

Mandelbrot set zoomed in

Mandelbrot sets have the property of self-similarity.

That is, we can zoom in on any section of the chart and see the same fractal geometry playing out on infinitely smaller scales. This is but one of the astonishing properties of the Mandelbrot set.

Google Sheets is definitely not the best tool for exploring the Mandelbrot set at increasing resolution. It's too slow to render graphically and too manual to make the changes to the formulas and axis bounds.

However, as the maxim says: the best tool is the one you have to hand.

So, if you want to explore in Google Sheets it is possible:

Generating Zoomed Data

I'm going to zoom in on the point: -0.17033700000, -1.06506000000

(Thanks to this article, The Mandelbrot at a Glance by Paul Bourke, which highlighted some interesting points to explore.)

Starting with this formula in cell A2 to generate the 6,561 data points (I wouldn't recommend going above this because it becomes too slow):

=ArrayFormula(UNIQUE({
MOD(SEQUENCE(1681,1,0,1),41)/20,
ROUNDDOWN(SEQUENCE(1681,1,0,1)/41)/20;
-MOD(SEQUENCE(1681,1,0,1),41)/20,
ROUNDDOWN(SEQUENCE(1681,1,0,1)/41)/20;
MOD(SEQUENCE(1681,1,0,1),41)/20,
-ROUNDDOWN(SEQUENCE(1681,1,0,1)/41)/20;
-MOD(SEQUENCE(1681,1,0,1),41)/20,
-ROUNDDOWN(SEQUENCE(1681,1,0,1)/41)/20
}))

In columns C and D, I transformed this data by change the 0,0 center to -0.17033700000, -1.06506000000 and then adding the values from A and B to C and D respectively, divided by 100 to zoom in.

=C$2+A3/100
=D$2+B3/100

The rest of the process is identical.

I set the chart axes min and max values to match the min and max values in each of column C (x axis) and D (y axis).

Mandelbrot set zoomed in

This looks continuous because the chart has a point size of 10px to make it look better.

If I reset that to 2px, you can see clearly that this is still a scatter plot:

Mandelbrot scatter plot

I hope you enjoyed that exploration of the Mandelbrot set in Google Sheets! Let me know your thoughts in the comments below.

Complex Numbers in Google Sheets

Complex numbers are numbers in the form a + bi, where i is the square root of -1.

What on earth does that mean?

Imaginary And Complex Numbers

To start, consider an integer, say the number 4. The square root of 4 is 2. Easy peasy.

Now consider -4. What’s the square root of that?

It’s not -2, because -2 * -2 = 4 (a minus multiplied by a minus is a positive in mathematics).

No real number will equal the square root of – 4, so we need a new number.

This new number is called an imaginary number (no, I didn’t just make that up!) and is denoted by i and defined as the square root of -1.

i = √-1

or put another way:

i² = -1

A complex number is a number that has real and imaginary parts, and can be expressed in the form:

a + bi

where a and b are real numbers and i is the imaginary number defined above.

We can look at complex numbers visually in a 2-dimensional plane, with the x-axis representing the real numbers and the y-axis representing the imaginary numbers:

Complex Number Plane

Complex numbers are usually represented by the letter z, and written:

z = a + bi

Let’s go and create one in Google Sheets!

Complex Numbers In Google Sheets

Let’s create a complex number in Google Sheets.

Starting in a blank Sheet, add the numbers 3 and 2 into cells A1 and B1 respectively.

In C1, add this formula with the COMPLEX function:

=COMPLEX(A1,B1,"i")

This is what our complex number looks like in Google Sheets:

Complex Number Function in Google Sheets

Size Of A Complex Number

We can calculate the size of a complex number, called its absolute value or modulus value and written |z|, by measuring how far it is from the center point (0,0).

We do this using the Pythagorean formula for the longest side of a right angle triangle, namely the square root of the squares of the other two sides.

Google Sheets has a handy function, called IMABS, that will calculate this value for us.

Put this formula into cell D1:

=IMABS(C1)

It gives the result 3.605551275.

Complex Number size in Google Sheets

This is the same as doing the square root of the squares of the other two sides:

=SQRT(3^2+2^2)

Answer 3.605551275.

Adding Complex Numbers

The next operation we need to know how to do with complex numbers is how to add them.

What’s 3 + 2i added to 5 + 7i?

To get the answer we add the real parts and imaginary parts separately, and combine into a new complex number.

So

z = (3 + 2i) + (2 + 7i)
= (3 + 2) + (2i + 7i)
= 5 + 9i

Back in our Google Sheet, I’ve added a new row for the new complex number and used the IMSUM function to add them together:

=IMSUM(C1:C2)

which looks like this in our Google Sheet:

Adding complex numbers in Google Sheets

Squaring Complex Numbers

Another operation we need to perform on our complex numbers is to square them.

The IMPOWER function does the trick. It returns a complex number raised to a power.

In our Google Sheet, use this formula in cell D1:

=IMPOWER(C1,2)

which gives the answer 5 + 12i, calculated as follows:

(3 + 2i)² = (3 + 2i) * (3 + 2i)
= 3 * 3 + 2i * 3 + 3 * 2i + 2i * 2i
= 9 + 6i + 6i + 4 * i²
= 9 + 12i + 4 * -1
= 9 - 4 + 12i
= 5 + 12i

Extracting Real And Imaginary Parts

You can use the IMREAL function to return the real coefficient of a complex number (the “a” part).

And IMAGINARY function returns the imaginary coefficient (the “b” part).

There are other, more specialized complex numbers functions in Google Sheets too, but they’re beyond the scope of this article.

Why Are Complex Numbers Useful?

For mathematicians, complex numbers are just as “real” as the real numbers.

They have applications in many areas of mathematics, physics and engineering.

One area where you may have seen them without realizing, is in fractal geometry and specifically pictures of a beautiful set of complex numbers called the Mandelbrot set:

How to draw a Mandelbrot Set in Google Shetes

Here’s How To Draw The Mandelbrot Set In Google Sheets.

Formula Challenge #4: Sort A Column By Last Name

This Formula Challenge originally appeared as Tip #108 of my weekly Google Sheets Tips newsletter, on 29 June 2020. Sign up so you don’t miss future Formula Challenges!

Find all the Formula Challenges archived here.

The Challenge: Sort A Column By Last Name

Start with a list of any ten two-word names in column A, like so:

Formula Challenge 4

Your challenge is to create a single formula in cell B1 (shown in yellow below) that sorts this list alphabetically by the last name, like this:

Sort Column By Last Name

Assumptions:

  • The names to sort are in the range A1:A10
  • Each name consists of a first name and last name only, with a single space between them
  • None of the names have prefixes or suffixes
  • The formula in cell B1 should output the full names in range B1:B10

Solutions To Sort A Column By Last Name

I received over 90 replies to this formula challenge with at least 10 different methods for solving it. This was super interesting to see!

Congratulations to everyone who took part.

I learnt so much from the different replies, many of which proffered shorter and more elegant solutions than my own original formula.

Here I present the best 4 solutions, chosen for their simplicity and elegance.

There’s a lot to learn by looking through them.


1. SORT/INDEX/SPLIT method

Solution:

Use this formula in cell B1 to sort the data alphabetically by the last name:

=SORT(A1:A10,INDEX(SPLIT(A1:A10," "),,2),1)

This is a beautiful solution.

It’s deceptively simple, as you’ll see below when we break it down. And yet, only a handful of people submitted this solution.

How does this formula work?

Let’s use the onion method to peel back the layers and build this formula in steps from the innermost layer.

Step 1:

Enter this formula as a starting point:

=SPLIT(A1:A10," ")

It takes the range A1:A10 as an input and splits the names on the space character. That works in this example because of our rigid assumptions that all names are two-word names.

The output is a single row with the name split across two cells. (Adding an ArrayFormula would give an output of all ten names, but it’s not required when we plug this split into the INDEX function.)

Step 2:

Wrap the formula from step 1 in an INDEX function:

=INDEX(SPLIT(A1:A10," "),,2)

Leave the row argument (the second argument) in the function blank and choose column 2 in the column argument (the third one). This formula outputs the list of second names, still in the original order however.

Step 3:

The SORT function takes three arguments: the range to sort, the column to sort on, and whether to sort ascending or descending.

So A1:A10, the range containing the full names, is the range we want to sort.

Then the column of last names created in step 2 is the column we want to sort on. This is our second argument.

Then the third argument is a TRUE or 1 to indicate we want to sort the names ascending.

So plugging these three arguments into the SORT function gives the following formula:

=SORT(A1:A10,INDEX(SPLIT(A1:A10," "),,2),1)

This formula can be modified to include the whole of column A if there are more than 10 names. Simply change the range from A1:A10 to A1:A as follows:

=SORT(A1:A,INDEX(SPLIT(A1:A," "),,2),1)

2. QUERY method

Solution:

Use this formula in cell B1 to sort the data alphabetically by the last name:

=ArrayFormula(QUERY({A1:A10,SPLIT(A1:A10," ")},"select Col1 order by Col3"))

Step 1:

Step 1 is the same as the step 1 in solution 1 above, and uses the SPLIT to separate the names into first and last names in separate columns:

=SPLIT(A1:A10," ")

Step 2:

Step 2 combines these two split columns with the original column of names using curly braces to construct an array of full name, first name and last name.

=ArrayFormula({A1:A10,SPLIT(A1:A10," ")})

The ArrayFormula wrapper is necessary to output all 10 values in this example.

Step 3:

The array created by step 2 is used as the input data range in the QUERY function in step 3:

=ArrayFormula(QUERY({A1:A10,SPLIT(A1:A10," ")},"select Col1 order by Col3"))

Since the input range of the QUERY function is constructed with the curly brace notation {…} we are required to use the Col1, Col2, etc. notation to access the columns. The query clause is pretty simple. Select only column 1 of the array (the full name) but sort by column 3 (the last name).

Note, the ArrayFormula can be brought outside the QUERY to be the outer wrapper.

This formula can be extended easily to the whole of column A by changing the range to A1:A and adding a WHERE clause to filter out the blank rows:

=ArrayFormula(QUERY({A1:A,SPLIT(A1:A," ")},"select Col1 where Col1 is not null order by Col3"))

3. REGEX method I

Solution:

Use this formula in cell B1 to sort the data alphabetically by the last name:

=INDEX(SORT(REGEXEXTRACT(A1:A10,"((.*)( .*))"),3,1),,1)

If the first solution was the shortest and simplest, then this is perhaps the most elegant.

It only references the data range A1:A10 once, whereas all the other solutions presented here reference the data range twice.

Step 1:

Use the REGEXEXTRACT function to split the data into three columns of full name, first name and last name:

=REGEXEXTRACT(A1:A10,"((.*)( .*))")

The REGEX functions in Google Sheets use the re2 flavor of regex.

This formula uses numbered capturing groups to capture the data, denoted by (.*) and ( .*) with the second having a space. The .* simply says match zero or more of any character.

In other words the (.*)( .*) construction separates into first and last names. Adding another matching group with the additional parentheses ((.*)( .*)) also matches the full name.

These three columns are passed into the SORT function in STEP 2:

Step 2:

=SORT(REGEXEXTRACT(A1:A10,"((.*)( .*))"),3,1)

The data is sorted on column 3 containing the last name. The 1 represents a TRUE value which sorts the data ascending from A-Z.

Step 3:

In the final step, we use the INDEX function to return only the first column, which has the full name.

=INDEX(SORT(REGEXEXTRACT(A1:A10,"((.*)( .*))"),3,1),,1)

4. REGEX method II

Solution:

Use this formula in cell B1 to sort the data alphabetically by the last name:

=SORT(A1:A10,REGEXEXTRACT(A1:A10,"(?: )(\w*)"),1)

This is the same method as the first solution, but uses REGEXEXTRACT instead of INDEX/SPLIT. So it’s one less function, but the REGEXEXTRACT function is much harder to understand than the INDEX/SPLIT combination for those unfamiliar with the black magic of regular expressions.

Step 1:

Use the REGEXEXTRACT function to extract the last names from the data:

=REGEXEXTRACT(A1:A10,"(?: )(\w*)")

The (?: ) is a non-capturing group matching the space. In other words the REGEXEXTRACT matches the space but doesn’t extract it.

The \w character matches word characters (≡ [0-9A-Za-z_]) and the * means match zero or more word characters but prefer more.

The parentheses ( ) around the \w* make it a captured group so it’s extracted.

See, regular expressions are as clear as mud.

Ok, so what’s happening is that it matches on the space, but doesn’t return it. Then it matches on the word group that follows the space and returns that. Hence we get an output range of last names only.

Step 2:

The final step is to sort range A1:A10 using the last names extracted in step 2, and sort them ascending. This step is identical to the implementation in solution 1.

=SORT(A1:A10,REGEXEXTRACT(A1:A10,"(?: )(\w*)"),1)

This formula can be modified to include the whole of column A if there are more than 10 names. Simply change the range from A1:A10 to A1:A as follows:

=SORT(A1:A,REGEXEXTRACT(A1:A,"(?: )(\w*)"),1)

There we go!

Four brilliant solutions to an interesting formula challenge.

Please leave comments if you have anything you wish to add.

And don’t forget to sign up to my Google Sheets Tips newsletter so you don’t miss future formula challenges!