Exercise 15.1
1. Using divisibility rules, find which of the following numbers are divisible by 2, 5, 10 (say yes or no) in the given table. What do you observe?
Solution:
| Number | Divisible by 2 | Divisible by 5 | Divisible by 10 |
|---|---|---|---|
| 524 | |||
| 1200 | |||
| 535 | |||
| 836 | |||
| 780 | |||
| 3005 | |||
| 4820 | |||
| 48630 |
2. Using divisibility tests, determine which of the following numbers are divisible by 2:
(a) 2144
Solution:
Divisible by 2:
(b) 1258
Solution:
Divisible by 2:
(c) 4336
Solution:
Divisible by 2:
(d) 633
Solution:
Divisible by 2:
(e) 1352
Solution:
Divisible by 2:
3. Using divisibility tests, determine which of the following numbers are divisible by 5:
(a) 438750
Solution:
Divisible by 5:
(b) 179015
Solution:
Divisible by 5:
(c) 125
Solution:
Divisible by 5:
(d) 639210
Solution:
Divisible by 5:
(e) 17852
Solution:
Divisible by 5:
4. Using divisibility tests, determine which of the following numbers are divisible by 10:
(a) 54450
Solution:
Divisible by 10:
(b) 10800
Solution:
Divisible by 10:
(c) 7138965
Solution:
Divisible by 10:
(d) 7016930
Solution:
Divisible by 10:
(e) 10101010
Solution:
Divisible by 10:
5. Write the number of factors for the following:
Solution:
18 =
24 =
45 =
90 =
105 =
6. Write any 5 numbers which are divisible by 2, 5 and 10.
Solution:
Any number ending in
=
7. A number 34A is exactly divisible by 2 and leaves a remainder 1, when divided by 5, find A.
Solution:
Since 34A is divisible by 2, A must be an
Since 34A leaves a remainder of 1 when divided by 5, A must be
The only digit that satisfies both conditions is