CHAPTER 1 : Real Numbers

Exercise 1.2

1. Express each number as a product of its prime factors :
1. 140 answer
2. 156 answer
3. 3825 answer
4. 5005 answer
5. 7429 answer
2. Find the LCM and HCF of the following pairs of integers and verify that LCM ⨯ HCF = product of the two numbers
1. 26 and 91 answer
2. 510 and 92 answer
3. 336 and 54 answer
3. Find the LCM and HCF of the following integers by applying the prime factorisation method.
1. 12, 15 and 21 answer
2. 17, 23 and 29 answer
3. 8, 9 and 25 answer
4. Given that HCF (306, 657) = 9, find LCM (306, 657). answer
5. Check whether 6ⁿ can end with the digit 0 for any natural number n. answers
6. Explain why 7 × 11 × 13 + 13 and 7 × 6 × 5 × 4 × 3 × 2 × 1 + 5 are composite numbers. answers
7. There is a circular path around a sports field. Sonia takes 18 minutes to drive one round of the field, while Ravi takes 12 minutes for the same. Suppose they both start at the same point and at the same time, and go in the same direction. After how many minutes will they meet again at the starting point? answers