3rd Class Mathematics Addition and Subtraction

Addition and Subtraction

Concept of Zero:

• Zero added to any number is equal to the number itself.

Example: 243 + 0 = 243

Addition:

• While adding, if we change the order of the numbers, the result will be the same.
• Addition of 3-digit numbers is done by arranging the digits of ones, tens and hundreds in their proper place.
• First we add ones, then tens and then hundreds.

Addition of 3-digit numbers without carrying:

Example: Add 376 and 213

Solution:

Step- 1: Arrange the numbers according to their proper place values.

Step-2: Add the ONES first, then the TENs and finally the HUNDREDS.

• Addition of3-digit numbers with carrying :

Example: Add 498 and 376

Solution:

Step-1: Arrange the digits of the numerals in proper places.

• Step -2: Add ones

8+6=14

14 ones = 1 ten + 4 ones

1 ten is carried to tens column. 4 is written in ones place.

Step - 3: Add tens

1 + 9 + 7 = 17

17 tens = I hundred + 7 tens

1 hundred is carried to hundreds column.

7 is written in tens place.

Step - 4: Add Hundreds

1+4+3=8

8 is written in Hundreds place.

Subtraction:

• Zero subtracted from any number is equal to the number itself.
• First we subtract ones, then tens and then hundreds.

Subtraction of3-digitnumbers without borrowing:

Ex: Subtract 652 from 956

Step - 1: Arrange the numbers according to their proper place values.

Step-2: Subtract ONES first, then the TENS and finally the HUNDREDS.

• Subtraction of 3 - digit numbers with borrowing:

Ex : Subtract 652 from 831.

Step-1: Arrange the numbers according to their proper place values.

Step - 2: Subtract ONES

1 – 2 = ?

We can't subtract 2 from 1.     

3 tens become 2 tens.

Subtract, 11 - 2 = 9

Borrow 1 ten from 3 tens.

1 one become 10 + 1 = 11 ones

Write 9 in ones place

Step - 3: Subtract TENS

We can't subtract "5 from 2.     

8 hundreds become 7 hundreds.

Borrow 1 hundred

2 tens become 10 + 2 = 12 tens.

from 8 hundreds.

Subtract, 12 - 5 = 7            Write 7 in tens place

• Step - 4: Subtract HUNDREDS

7-6=1

So we write 1 in place of hundreds.

Thus we get 831 - 652 =