You are here:

Question
I am a grandmother finding it difficult to help my grandson with his math. my question is; what is regrouping?

Hello, Karen.

Regrouping is a method used in addition when one of the columns (ones, tens, hundreds, etc.) totals more than 9.

For 24 + 68, 8 and 4 are in the ones column. 8+4 = 12, but you can't write 12 below for part of the sum. You have to regroup.

To do this, place the 2 below the 8 and the 4, and then 'regroup' the 1: place the 1 above the 2 in the tens column. So, instead of adding 6 and 2, you are adding 1+6+2 in the tens column, giving you 9.

Regrouping (or borrowing) is also used for subtraction. If, for example, you have 25-8, you must regroup, or borrow, from the 2 (because you cannot subtract 8 from 5 in this example). When you borrow from the 2, it becomes a 1, and the 5 above the 8 becomes a 15. So, you then would have 1 (15) - 8.

15-8 is 7, and 1-0 is 1. So, your answer is 17.

I hope this helps.

Regards,
John

Basic Math

Volunteer

#### John Zalewski

##### Expertise

I can help you solve problems involving fractions, decimals, ratios, and algebra. I can teach you how to do math faster, and even in your head. I can teach math definitions, and help you study, if necessary. Please do not ask any graphing, trigonometry, or calculus questions. Try to work through homework questions before asking for assistance.

##### Experience

I routinely process numbers of all kinds in my head, without need of a calculator.

Education/Credentials
I was an A math student while in high school.