Page 87 - ICSE Math 4

Divisibility Divisibility Rule Example
by

A number is divisible by 2, if the digit 128 is divisible by 2 since the digit

2 at its ones place is even, i.e., 0, 2, 4, at the ones place is even.
6 and 8.

A number is divisible by 3, if the sum 234 is divisible by 3 since the sum
3 of all its digits is divisible by 3. of all its digits, i.e., 2 + 3 + 4 is 9,
which is divisible by 3.

A number is divisible by 4, if the 3,596 is divisible by 4 since the
number formed by its last two digits number formed by the last two
4
(i.e., ones and tens) is divisible by 4. digits of the number, i.e., 96 is
divisible by 4.

A number is divisible by 5, if the digit 1,565 is divisible by 5 since the
5
at its ones place is either 0 or 5. digit at the ones place is 5.

A number is divisible by 9, if the sum 3,402 is divisible by 9 since the
9 of all its digits is divisible by 9. sum of all its digits, i.e., 3 + 4 + 0 +
2 is 9, which is divisible by 9.

A number is divisible by 10, if the digit 4,250 is divisible by 10 since the
10
at its ones place is 0. digit at the ones place is 0.

Example 11: Is 286 divisible by 2?

Solu on: In 286, 6 at the ones place is an even number. So 286 is divisible by 2.
Example 12: Is 342 divisible by 3?

Solu on: 342
3 + 4 + 2 = 9

Since the sum of all the digits of 342 is 9, it is divisible by 3.

Example 13: Is 140 divisible by 5?
Solu on: In 140, the digit at the ones place is 0. So 140 is divisible by 5.

Exercise 7.4

1. Which of the following numbers are divisible by 2?

(a) 96 (b) 132 (c) 443 (d) 105 (e) 274 (f) 370

77