Count by 90 (Skip Counting by 90s)

Count by 90

Here we will show you how to count by 90, discuss counting by 90 patterns, and tell you why knowing how to count by 90 matters. To start off, note that Count by 90 means counting in 90s, or count by nineties, and it is also called skip counting by 90.

How to count by 90
Normally, we would count by 1 like this: 1, 2, 3, 4, etc., but when we count by 90, we count 90, 180, 270, 360, and so on.

In other words, to count in intervals of 90 or skip counting by 90, we start with 90 and then add 90 to get the next number, and then continue adding 90 to the previous number to keep counting by 90, like this:

90
90 + 90 = 180
180 + 90 = 270
270 + 90 = 360
360 + 90 = 450
...

You can of course skip count by 90 forever, so it is impossible to make a list of all numbers, but below is a Count by 90 Chart of the first 100 numbers to get you started.

Looking at the chart above, you will see that the first column has the first ten numbers you get when you skip count by 90, the second column has the next ten numbers you get when you skip count by 90, and so forth.

Count by 90 Patterns
We organized the Skip Counting by 90s Chart above in 10 rows and 10 columns so you can easily identify patterns.

Skip counting always creates patterns. Figuring out these patterns may help you if want to count by 90, but don't have the Counting by 90s Chart above. Obviously, one pattern with counting by 90s is that the number increases by 90.

Furthermore, if you look at each row above, each number in the row has the same last digit (ones place). That means that every tenth number has the same last digit.

If you look down the columns, you will see that the last digit (ones place) repeats itself in blocks of 1 over and over. The pattern of the last digit when you count by 90 goes 0 and 0 and so on for as long as you count by 90.

Why Count by 90?
We think that understanding and learning about skip counting by 90 is important, because it teaches you how the arithmetic operations fit together. Below are some examples of what we mean.

When you count by ninety, you are also creating a list of multiples of 90 that you can use in math when you need the least common multiple. 90 times n equals the nth multiple or skip count of 90.

When you skip count by 90, you are also creating a list of numbers that 90 is divisible by. On top of that, skip counting by 90 is the same as making the 90 times table.

Skip Counting
Need to skip count by another number? Enter another number for us to skip count for you.

Count by 91
Here is the next number on our list that we used to skip count.