Wednesday, 7 March 2012

CBSE Class 6th ( VI) Mathematics Chapter 3. Playing with Numbers :Exercise 3.1

1. Write all the factors of the following numbers :
(a) 24(b) 15 (c) 21
(d) 27 (e) 12 (f) 20
(g) 18 (h) 23 (i) 36
Answer:
(a) 24
  • 24 = 1 × 24
  • 24 = 2 × 12
  • 24 = 3 × 8
  • 24 = 4 × 6
Thus, the factors of 24 are 1, 2,3, 4, 6, 8, 12 and 24.
(b) 15
  • 15 = 1 × 15
  • 15 = 3 × 5
Thus, the factors of 15 are 1, 3, 5, and 15.
(c) 21
  • 21 = 1 × 21
  • 21 = 3 × 7
Thus, the factors of 21 are 1, 3,7 and 21.
(d) 27
  • 27 = 1 × 27
  • 27 = 3 × 9
Thus, the factors of 27 are 1, 3,9 and 27.
(e) 12
  • 12 = 1 × 12
  • 12 = 2 × 6
  • 12 = 3 × 4
Thus, the factors of 12 are 1, 2, 3, 4, 6 and 12.
(f) 20
  • 20 = 1 × 20
  • 20 = 2 × 10
  • 20 = 4 × 5
Thus, the factors of 20 are 1, 2, 4, 5, 10 and 20.
(g) 18
  • 18 = 1 × 18
  • 18 = 2 × 9
  • 18 = 3 × 6
Thus, the factors of 18 are 1, 2, 3, 6 and 18.
(h) 23
  • 23 = 1 × 23
Thus, the factors of 23 are 1 and 20.
(h) 36
  • 36 = 1 × 36
  • 36 = 2 × 18
  • 36 = 3 × 12
  • 36 = 4 × 9
  • 36 = 6 × 6
Thus, the factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18 and 36
2. Write first five multiples of :
(a) 5(b) 8 (c) 9
Solution :
(a) 5
  1. 5 × 1 = 5
  2. 5 × 2 = 10
  3. 5 × 3 = 15
  4. 5 × 4 = 20
  5. 5 × 5 = 25
Thus, The required first five multiples of 5 are 5, 10, 15, 20 and 25.
(b) 8
  1. 8 × 1 = 8
  2. 8 × 2 = 16
  3. 8 × 3 = 24
  4. 8 × 4 = 32
  5. 8 × 5 = 40
Thus, The required first five multiples of 5 are 8, 16, 24, 32 and 40.
(c) 9
  1. 9 × 1 = 9
  2. 9 × 2 = 18
  3. 9 × 3 = 27
  4. 9 × 4 = 36
  5. 9 × 5 = 45
Thus, The required first five multiples of 5 are 9, 18, 27, 36 and 45.
3. Match the items in column 1 with the items in column 2.
Column 1Column 2
  • 35
  • 15
  • 16
  • 20
  • 25
  • Multiple of  8
  • Multiple of  7
  • Multiple of  70
  • Factor of  30
  • Factor of  50
  • Factor of  20
Answer:
Column 1Column 2
  • 35
  • 15
  • 16
  • 20
  • 25
(b) Multiple of  7

(d) Factor of  30

(a) Multiple of  8

(f) Factor of  20

(e) Factor of  50

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