MathMaster Blog

Subtraction is the opposite operation of addition. Long subtraction is a method for subtracting numbers. It entails writing the numbers to be subtracted one beneath the other in columns. We subtract numbers a column at a time.

How to do the long subtraction:

• Step 1: Write the numbers you want to subtract, one underneath the other.
• Step 2: Check if the number at the top of the column is larger than or equal to the number at the bottom of the column:

if yes, subtract the numbers, write the answer below the column (between the lines) and move to Step 3.

if no, borrow a digit from the top number in the column to the left. Cross out the top number on the column to the left, and write the number one less than it in its place. Write 1 in front of the top number in the subtracting column. The number will be 10 plus the number. Subtract the numbers, write the answer below the column (between the lines) and move to Step 3.

• Step 3: Move to the column to the left.
• Step 4: Go to Step 2 and repeat until all columns have been subtracted.

Example

Solve 246 - 158.

Solution:

Step 1:

Set up the problem in a long subtraction format

Step 2:

The number at the top of the column is larger than or equal to the number at the bottom (6 < 8).

So, borrow a digit from the top number in the column to the left. Instead of the top number on the column to the left (4) write the number one less (3) than it in its place.

Step 3:

‘Borrow’ the 1 and make 6 a 16

Subtract the numbers and write the answer below the column (between the lines).

16 - 8 = 8

Step 4:

Move to the column on the left. As the number at the top of column (3) is not larger than or equal to the number at the bottom of column (5), you need to borrow a digit from the top number in the column to the left. Instead of the top number on the column to the left (2) write the number one less (1) than it in its place.

‘Borrow’ the 1 and make 3 a 13. Then subtract the numbers and write the answer below the column (between the lines)

13 - 5 = 8

Move to the column to the left

Step 5:

Check if the number at the top of the column is larger than or equal to the number at the bottom.

Yes. 1 is larger than or equal to 1. So, subtract the numbers, and write the answer below the column (between the lines).

1 - 1 = 0

All columns have been subtracted.

Answer: 88