Page 57 - Start Up Mathematics_1

Addition Facts

1. We can add two numbers in any order. The answer will be the same.

2 + 5 = 7 = 5 + 2

+ = + =

2. On adding zero to a number, the number remains unchanged.

6 + 0 = 6 = 0 + 6

+ = + =

Addition of 2-Digit and 3-Digit Numbers

To add a 2-digit number with a 3-digit number, first add the ones, then the
tens and finally keep the hundreds.

Common Mistake!
H T O
1 4 2
Always write the numbers
in their correct place. + 3 6 ()

Look at the given example.

H T O H T O H T O
1 4 2 1 4 2 1 4 2

+ 3 6 + 3 6 + ↓ 3 6

8 7 8 1 7 8

Step 1: Add the ones. Step 2: Add the tens. Step 3: Keep the
2 + 6 = 8 4 + 3 = 7 hundreds.

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