Subtraction with Decomposition 2-Digit Number from 2-Digit Number

In subtraction with decomposition 2-digit number from 2-digit number we will learn how to regroup when subtracting two digit numbers. Here we will practice the subtraction and unlike these examples, we will do involve decomposition (borrowing from the left side column).

How to solve subtraction with decomposition – Tens and Units?

Consider the following examples on subtraction with decomposition (2-digit number from 2-digit number). Step-by-step we will learn subtracting two numbers with borrowing.

1. 32 - 17

In the problem we cannot subtract or take 7 from 2 in the ones place column since 7 is bigger than 2. Suppose, if you have only 2 mangoes, your sister can’t take 7 mangoes away from you. So, we need to use the process called decomposition. Decomposition happens or required when we borrow an amount from the number on the left to give it to the number on the right. We only apply this in the top row numbers.

What this means here is that we can’t take 7 from 2 so we borrow a ten from the next column along (the 3). We will take 10 off the left side number (3) and give it to the right side number (2). The 3 is in the tens column, so it represents 30 (3 × 10). Taking 10 off 30 leaves 20 (2) and adding 10 to 2 gives 12.

 32

-17

We can now subtract 7 from 12 in the ones column to get 5.

 32

-17

   5

Next, we subtract 1 from 2 in the tens column to get 1.

 32

-17

 15

And the difference is 32 – 17 = 15.

2. 56 - 29

In the problem we cannot subtract or take 9 from 6 in the ones place column since 9 is bigger than 6. Suppose, if you have only 6 mangoes, your sister can’t take 9 mangoes away from you. So, we need to use the process called decomposition. Decomposition happens or required when we borrow an amount from the number on the left to give it to the number on the right. We only apply this in the top row numbers.

What this means here is that we can’t take 9 from 6 so we borrow a ten from the next column along (the 5). We will take 10 off the left side number (5) and give it to the right side number (6). The 5 is in the tens column, so it represents 50 (5 × 10). Taking 10 off 50 leaves 40 (4) and adding 10 to 6 gives 16.

 56

-29

We can now subtract 9 from 16 in the ones column to get 7.

 56

-29

   7

Next, we subtract 2 from 4 in the tens column to get 2.

 56

-29

 27

And the difference is 56 – 29 = 27.

2nd Grade Math Practice

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