Page 49 - Revised Maths Wisdom Class - 6

Prime Time 47

5. Write all the composite numbers less than 10. Find their product and express it as the product of prime numbers.
6. Test the divisibility of the following by 2, 3 and 6.
(a) 980 (b) 437 (c) 102 (d) 564
7. Check the divisibility of the following by 3, 4, 8 and 9.
(a) 96128 (b) 298704 (c) 120357 (d) 687352

8. Check the divisibility of the following by 5 and 10.
(a) 9999 (b) 100005 (c) 2347850 (d) 686855
9. Using divisibility rules, determine which of the following are divisible by 11:
(a) 50007001 (b) 3176985 (c) 96010837

10. In each of the following replace * by the smallest number so that the given number is divisible by the number
mentioned:
(a) 84*3 by 3 (b) 817*67 by 11 (c) 4347* by 4 (d) 85*63 by 9
11. A number is divisible by 18. By what other numbers will it be divisible?
12. Which of the following are prime numbers:
(a) 116 (b) 293 (c) 331 (d) 217

13. Give an example of a number which is divisible by:
(a) 3 but not 9 (b) 4 but not 8 (c) 2 but not 4 (d) both 4 and 8 but not 12
14. Find the smallest and the greatest digit so that the number formed is divisible by given divisor:

(a) 8325 by 3 (b) 13 471 by 11
15. Give an example to show that if two numbers are divisible by the given number, then the sum of the two
numbers is also exactly divisible by the same number.

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

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COMPETENCY BASED QUESTIONS

A Oral Quiz Oral Quiz

1. Express 60 as the sum of two prime numbers. 4. A number divisible by 3 is also divisible by 9.
2. Write the smallest even and odd prime numbers. Write True or False.

3. Is 9817 completely divisible by 3? 5. Write any pair of twin prime.