Two- and three-digit numbers ending in zero can sometimes be difficult to work with when solving a problem. This is especially true when it comes to subtraction problems where the top number has a zero in the ones place (ones colu­mn). So what can we do when this happens?

Simple-we can rename two- and three-digit numbers that have a zero in the ones place by rewriting them as an equation of a number added to 1. Let's use th­e number 30 as an example:

We need to find an equation that ends in 30, but one of the addends(numbers added together) equals 1.


What number can we add to 1 that makes the equation equal 30? We can add 29.

30 = 29 + 1

Let's do another one. How about 80? Remember, one of the addends must be 1. We are reducing 80 by 1. What is the other addend?

The other addend equals 79.

80 = 79 + 1­

Let's try again, this time using a three-digit number. Let's rename 300. Again, one of the addends must be 1. Taking 1 away, what number is left?

The addend equals 299.

300 = 299 + 1

Let's try another one, this time using the greatest three-digit hundreds number, 900. We're going to rename the number by rewriting it as an equation with a number and 1. What is the number?

The addend equals 899.

900 = 899 + 1