Chapter 8 Divisibility
Question 1.
There are some flowering trees in a garden. Each tree bears many flowers with the same number printed on it. Three children took a basket each to pick flowers. Each basket has one of the numbers, 3, 4 or 9 on it. Each child picks those flowers which have numbers divisible by the number on his or her basket. If He / She takes only 1 flower from each tree. Can you tell which numbers the flowers in each basket will have?
Solution:
Each child will have flowers bearing the following numbers:
Girl with basket number 3: 111, 369, 435, 249, 666, 450, 960, 432, 999, 72, 336, 90, 123, 108
Boy with basket number 4: 356, 220, 432, 960, 72, 336, 108
Girl with basket number 9: 369, 666, 450, 432, 999, 72, 90, 108
Intext Questions and Activities
Question 1.
Read the numbers given below. Which of these numbers are divisible by 2, by 5, or by 10? Write them in the empty boxes. 125,364,475,750,800,628,206,508,7009,5345,8710. (Textbook pg. no. 43)
Divisible by 2 | Divisible by 5 | Divisible by 10 |
Solution:
Divisible by 2 | Divisible by 5 | Divisible by 10 |
364,750, 800, 628, 206, 508, 8710 | 125,475, 750, 800, 5345, 8710 | 750, 800, 8710 |
Question 2.
Complete the following table: (Textbook pg. no. 43)
Number | Sum of digits in the number | Is the sum divisible by 3? | Is the given number divisible by 3? |
63 | 6 + 3 = 9 | ✓ | ✓ |
872 | 17 | X | X |
91 | |||
552 | |||
9336 | |||
4527 |
Solution:
Number | Sum of digits in the number | Is the sum divisible by 3? | Is the given number divisible by 3? |
63 | 6 + 3 = 9 | ✓ | ✓ |
872 | 8 + 7 + 2 = 17 | X | X |
91 | 9 + 1 = 10 | X | X |
552 | 5 + 5 + 2 = 12 | ✓ | ✓ |
9336 | 9 + 3 + 3 + 6 = 21 | ✓ | ✓ |
4527 | 4 + 5 + 2 + 7 = 18 | ✓ | ✓ |
Question 3.
Complete the following table: (Textbook pg. no. 44)
Number | Divide the number by 4. Is it completely divisible? | The number formed by the digits in the tens and units places. | Is this number divisible by 4? |
992 | ✓ | 92 | ✓ |
7314 | |||
6448 | |||
8116 | |||
7773 | |||
3024 |
Solution:
Number | Divide the number by 4. Is it completely divisible? | The number formed by the digits in the tens and units places. | Is this number divisible by 4? |
992 | ✓ | 92 | ✓ |
7314 | X | 14 | X |
6448 | ✓ | 48 | ✓ |
8116 | ✓ | 16 | ✓ |
7773 | X | 73 | X |
3024 | ✓ | 24 | ✓ |
Question 4.
Complete the following table: (Textbook pg. no. 44)
Number | Divide the number by 9. Is it completely divisible? | Sum of the digits in the number. | Is the sum divisible by 9? |
1980 | ✓ | 1 + 9 + 8 + 0 = 18 | ✓ |
2999 | X | 2 + 9 + 9 + 9 = 29 | X |
5004 | |||
13389 | |||
7578 | |||
69993 |
Solution:
Number | Divide the number by 9. Is it completely divisible? | Sum of the digits in the number. | Is the sum divisible by 9? |
1980 | ✓ | 1 + 9 + 8 + 0 = 18 | ✓ |
2999 | X | 2 + 9 + 9 + 9 = 29 | X |
5004 | ✓ | 5 + 0 + 0 + 4 = 9 | ✓ |
13389 | X | 1 + 3 + 3 + 8 + 9 = 24 | X |
7578 | ✓ | 7 + 5 + 7 + 8 = 27 | ✓ |
69993 | ✓ | 6 + 9 + 9 + 9 + 3 = 36 | ✓ |