How to Do Long Subtraction
What Is Long Subtraction? (Interactive Widget)
Use this interactive widget to see a stepbystep explanation of long subtraction.

This is a randomly generated longsubtraction sum.

What Is Long Subtraction?
Long subtraction is a method for subtracting numbers.
Long subtraction involves writing the numbers to be subtracted one underneath another, so the digits are in columns. The numbers are subtracted a column at a time.
Many numbers of any length (including decimals) can be subtracted in this way.
How to Do Long Addition
StepbyStep:
1
Write the numbers you wish to subtract, one underneath the other.
2
Look at the numbers in the rightmost column.
3
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 4.

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 a 1 in front of the top number in the column you are subtracting. The number will be 10 plus the number, which will be larger than the bottom number in the column.
Subtract the numbers, write the answer below the column (between the lines) and move to Step 4.
4
Move to the column to the left.
5
Go to Step 3 and repeat until all columns have been subtracted.
A Real Example of How to Do Long Subtraction
Doing long subtraction is easy.
Question
Subtract the numbers below.
StepbyStep:
1
Write the numbers you wish to subtract, one underneath the other.
2
Look at the numbers in the rightmost column.
3
Check if the number at the top of the column is larger than or equal to the number at the bottom of the column:
No. 6 is not larger than or equal to 8.

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 (4), and write the number one less (3) than it in its place.

Write a 1 in front of the top number in the column you are subtracting. The number will be 10 plus the number, which will be larger than the bottom number in the column.

Subtract the numbers, write the answer below the column (between the lines) and move to Step 4.
16 − 8 = 8
4
Move to the column to the left.
5
Go to Step 3.
3
1^{st} repeat
Check if the number at the top of the column is larger than or equal to the number at the bottom of the column:
No. 3 is not larger than or equal to 5.

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 (2), and write the number one less (1) than it in its place.

Write a 1 in front of the top number in the column you are subtracting. The number will be 10 plus the number, which will be larger than the bottom number in the column.

Subtract the numbers, write the answer below the column (between the lines) and move to Step 4.
13 − 5 = 8
4
1^{st} repeat
Move to the column to the left.
5
1^{st} repeat
Go to Step 3.
3
2^{nd} repeat
Check if the number at the top of the column is larger than or equal to the number at the bottom of the column:
Yes. 1 is larger than or equal to 1.

If Yes, If Yes, subtract the numbers, write the answer below the column (between the lines).
1 − 1 = 0
There are no more columns to the left. All columns have been subtracted.
Answer:
The solution to 246 − 158 is 88.