To subtract one whole number from another we have to line up the numbers by place value. Subtract each number separately beginning from the right.
If I need to subtract 7 ones from 9 ones, I have to regroup and reach into the tens column and take 1 ten.
To begin with, I need to regroup 1 ten with the 8 into the ones column to make it 18 and then subtract 9.
Let us take an example.
Subtract 219 from 348
Step 1: Arrange the numbers in a column.
Step 2: Regroup 1 ten with 8 into the ones column and make it 18.
Step 3: Now subtract 9.
Step 4: There are only 3 ten’s in the tens column of 348, not 4.
Step 5: Now subtract the number in the tens column.
Step 6: Finally, subtract the number in the hundreds column.
The answer to the above example is 129.
318
348
 219
129
The numbers on the top row show the regrouping.Examples for Subtracting Whole Numbers
Given below are some examples on subtracting whole numbers
Example 1: Subtract 78 and 35
Solution: Given 78

35 ___
Step 1: First subtract the number in the one's place. Here 8 and 5 are in the one's place, so 8  5 = 3. The minuend number is larger than subtrahend so we continue the process.
78

35 3Step 2: Subtract the ten's place number. Here 7 and 3 are in the ten's place, so 7  3 = 4.
The minuend number is larger than subtrahend we continue the process.
78

35 43Answer : 43
Example 2: Subtract 145 and 126
Solution: Given 145

126 ____
Step 1: First subtract numbers 5 and 6 in the one's place. The minuend number is smaller than the subtrahend, so we borrow a number from the next place. Here
4 turns in to
3 at the ten's place after borrowing and
5 turns
15 at the one's place. So 15  6 = 9
1
35

126 9Step 2: Subtract the ten's place number. 3 and 2 are in the ten's place. So 3  2 = 1.
The minuend number is larger than the subtrahend we continue the process.
135

126 19Step 3: Subtract the hundred's place number. 1 and 1 are in the hundred's place. So 1  1 = 0.
The minuend number is larger than the subtrahend so we continue the process.
135

126 019Answer : 19
Word Problem on Subtraction:
Example: Sam is swimming in a 1600 meter event. He had already completed 500 meters of the race. How far does he have to swim to complete the race ?
Solution:
Operation : Subtraction
Distance = 1600  500
= 1100
Sam still has 1100 meters to swim.