CBSE Class 3 Mathematics Addition with and without Carrying Notes Set 01

Adding 3-digit and 4-digit numbers

Addition means putting numbers together to find the total. The answer is called the sum. In Class 3 we add numbers up to four digits, with carrying when needed.

Steps to add

1. Write the numbers one below the other so that ones are under ones, tens under tens, hundreds under hundreds and thousands under thousands.

2. Add the ones first. If the sum is 10 or more, write the ones digit and carry the tens digit to the tens column.

3. Add the tens column along with any carry. Carry again if needed.

4. Do the same for hundreds and then thousands.

Addition without carrying

When every column adds up to less than 10, no carrying is needed. Example: 2314 + 1523. Ones: 4 + 3 = 7. Tens: 1 + 2 = 3. Hundreds: 3 + 5 = 8. Thousands: 2 + 1 = 3. The sum is 3837.

Addition with carrying

When a column adds to 10 or more, we carry. Example: 4573 + 3968 + 1436.

1. Ones: 3 + 8 + 6 = 17. Write 7 and carry 1.

2. Tens: 7 + 6 + 3 = 16, plus the carry 1 gives 17. Write 7 and carry 1.

3. Hundreds: 5 + 9 + 4 = 18, plus the carry 1 gives 19. Write 9 and carry 1.

4. Thousands: 4 + 3 + 1 = 8, plus the carry 1 gives 9. Write 9.

The sum is 9977.

Useful facts

1. Order does not matter: 2756 + 342 = 342 + 2756.

2. Adding zero to a number leaves it unchanged: 345 + 0 = 345.

3. Odd + even = odd; even + even = even; odd + odd = even.

4. The smallest 4-digit number is 1000 and 10 tens make 1 hundred.

5. Words such as total, altogether, in all, sum, and more than tell us to add.

Word problems

Read the problem, find what is given, decide that we have to add, write the sum, and finish with a full answer sentence and unit such as ₹ for money.

Worked examples

Example 1. A number exceeds 6987 by 2478. What is the number?

Exceeds by means is more than, so we add. 6987 + 2478 = 9465. The required number is 9465.

Example 2. A gardener earns ₹4180. His salary increases by ₹100 every month for 7 months. What is his salary after 7 months?

Increase = 7 × ₹100 = ₹700. New salary = 4180 + 700 = ₹4880.

Example 3. In a town there are 915 male teachers and 829 female teachers. Find the total.

915 + 829: ones 5 + 9 = 14, write 4 carry 1. Tens 1 + 2 + 1 = 4. Hundreds 9 + 8 = 17. The total is 1744 teachers.

Checking your answer

1. Estimate first. 4573 is about 4600 and 3968 is about 4000, so 4573 + 3968 is about 8500. Your answer should be close to this.

2. Add again in reverse order: if the answer is the same, it is likely to be correct.

3. Subtract one of the numbers from the sum: 9465 − 6987 = 2478. This gives back the other number.

Place value and addition

Every digit has a value according to its place: ones, tens, hundreds and thousands. In 4573 the digit 4 is 4 thousands, 5 is 5 hundreds, 7 is 7 tens and 3 is 3 ones. Adding column by column keeps each place separate, and carrying moves ten of one place to the next bigger place.

Quick Check Questions