Addition of Three 1-Digit Numbers

To add three numbers, we add any two numbers first. Then, we add the third number to the sum of the first two numbers.

For example, let us add the numbers 3, 4 and 5.

We can write the numbers horizontally or vertically as shown below.

3 + 4 + 5 = 12

Note:

The order of numbers does not matter even when we are adding 3 numbers.

For example,

1 + 3 + 5 = 4 + 5 = 9 and

3 + 5 + 1 = 8 + 1 = 9

1. Add the following three 1-digit numbers numbers horizontally.

(i) 5 + 3 + 1 = _____

(ii) 6 + 3 + 9 = _____

(iii) 3 + 8 + 0 = _____

(iv) 6 + 3 + 2 = _____

(v) 8 + 9 + 2 = _____

(vi) 6 + 5 + 1 = _____

(vii) 7 + 1 + 4 = _____

(viii) 6 + 9 + 3 = _____

(ix) 5 + 5 + 4 = _____

Answer:

1. (i) 9

(ii) 18

(iii) 11

(iv) 11

(v) 19

(vi) 12

(vii) 12

(viii) 18

(ix) 14

2. Add the following three 1-digit numbers numbers vertically.

Answer:

2. (i) 9

(ii) 15

(iii) 11

(iv) 18

Word Problems on Addition of Three 1-Digit Numbers:

1. Nitheeya read 6 pages of a storybook on Monday, 7 pages on Tuesday and 5 pages on Wednesday. How many pages did he read in all?

Answer:

1. 18 pages

2. During summer vacation, Nairitee stayed at her grandmother's house for 8 days, at her uncle's house for 7 days and at her friend's house for 4 days. For how many days in all was she away from her home?

Answer:

1. 19 days

First Grade Math Activities

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