Playing with Numbers

Tests of divisibility

(i) Numbers are divisible by 10 if ones digit of a number is 0.

Eg:- 20, 30 ,40…

(ii) Numbers are divisible by 5 if ones digits are alternately 5 and 0.

Eg:- 5, 10, 15, 20….

(iii) Numbers are divisible by 2 if ones digit is 0, 2, 4,6 or 8.

Eg:-  10, 12, 14, 16, 18…

(iv) A number is divisible by 9 if the sum of its digits is divisible by 9. Otherwise it is not divisible by 9.

Eg:- Check if 108 is divisible by 9.

Ans-

Sum of digit of the number 108 = 1 + 0 + 8

= 9

9 is divisible by 9.

Hence, 108 is divisible by 9.

(v) A number is divisible by 3 if the sum of its digits is divisible by 3. Otherwise it is not divisible by 3.

Eg:- Check if 108 is divisible by 3.

Ans-

Sum of digit of the number 108 = 1 + 0 + 8

= 9

9 is divisible by 3.

Hence, 108 is divisible by 3.

Helping Topics

NCERT solutions, class 8

Practice sheet, class 8

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