(i) 140
(ii) 156
(iii) 8, 9 and 25
(i) 12, 15 and 21
(ii) 17, 23, and 29
(iv) 72 and 108
(v) 306 and 657
• Explain why 7 x 11 x 13 + 13 and 7 x 6 x 5 x 4 x 3 x 2 x 1 + 5 are co
numbers.
How will you show that (17 x 11 x 2) + (17 x 11 x 5) is a composite
Explain.
100
What is the last digit of 6
2. Find the LCM and HCF of the following integers by the puu
3. Check whether 6" can end with the digit 0 for any natural number n.
Answers
Answer:
Solution (i) To express the given number 140 as product of its prime factors, we employ the division method as shown below :
2 | 140
2 | 70
5 | 35
7 | 7
| 1
∴ 140 = 2×2×5×7
= 22×5×7
Solution (ii) To express the given number 156 as product of its prime factors, we employ the division method as shown below :
2 | 156
2 | 78
3 | 39
13 | 13
| 1
∴ 156 = 2×2×3×13
= 22×3×13
Solution (iii) To express the given number 3825 as product of its prime factors, we employ the division method as shown below :
3 | 3825
3 | 1275
5 | 425
5 | 85
17 | 17
| 1
∴ 3825 = 3×3×5×5×17
= 32×52×17
Solution (iv) To express the given number 5005 as product of its prime factors, we employ the division method as shown below :
5 | 5005
7 | 1001
11 | 143
13 | 13
| 1
∴ 5005 = 5×7×11×13
Solution (v) To express the given number 2429 as product of its prime factors, we employ the division method as shown below :
17 | 7429
19 | 437
23 | 23
| 1
∴ 7429 = 17×19×23