Page 50 - Maths Skill - 6

48 Maths

Exercise 3.5

1. Find the common multiples of the following numbers

(i) 3, 4, 5 (ii) 36, 84 (iii) 12, 24 (iv) 9, 12, 15
2. Find the common factors of the following numbers
(i) 54, 108, 144 (ii) 117, 81 (iii) 2103, 9945, 9216 (iv) 234, 78, 519

3. Find all the multiples of 30 that lie between 310 and 380
4. Find a number which is less than 40. One of its factor is 7 and the digit sum of that number is 8.

5. Find a number less than 100. Two of its factors are 3 and 5. One of its digits is 1 more than the other.
6. Find any three numbers that are multiples of 25 but not multiples at 50.
7. In the diagram below, Dhruv has erased all the numbers except the common multiples. Find out what
these numbers could be and fill in the missing numbers in the empty regions

Multiple of ........ Multiple of ........
28
56

Common multiple

AMUSEMENT WITH NUMBERS
Fill the grid with prime numbers only so that the product of each row is the number to the right of the row and the
product of each column is the number below the column.

5 7 11 385 7 5 3 105

13 17 3 663 2 5 2 20

2 19 23 874 2 5 3 30

130 2261 759 28 125 18

ASSESSMENT TIME

COMPETENCY BASED QUESTIONS 3. Which of the following pairs is a pair of
co-primes?
A. Multiple-Choice Questions (i) 9, 72 (ii) 12, 36
1. Which of the following is/are prime number(s)? (iii) 4, 9 (iv) 5, 20
(i) 247 (ii) 623 4. The largest number of four-digits which is

(iii) 739 (iv) 153 exactly divisible by 3 is:
2. The prime factors of 266 are: (i) 9995 (ii) 9990
(i) 2, 7, 19 (ii) 2, 3, 6 (iii) 9991 (iv) 9999
(iii) 3, 4, 3 (iv) none of these