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Playing With Numbers

NCERT Exercise 3.1

CBSE Class 6 Maths

**Q1. 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 = 1 × 24

= 2 × 12

= 3 × 8

= 4 × 6

= 6 × 4

∴ Factors of 24 = 1, 2, 3, 4, 6, 12, 24

(b) 15 = 1 × 15

= 3 × 5

= 5 × 3

∴ Factors of 15 = 1, 3, 5, 15

(c) 21 = 1 × 21

= 3 × 7

= 7 × 3

∴ Factors of 21 = 1, 3, 7, 21

(d) 27 = 1 × 27

= 3 × 9

= 9 × 3

∴ Factors of 27 = 1, 3, 9, 27

(e) 12 = 1 × 12

= 2 × 6

= 3 × 4

= 4 × 3

∴ Factors of 12 = 1, 2, 3, 4, 6, 12

(f) 20 = 1 × 20

= 2 × 10

= 4 × 5

= 5 × 4

∴ Factors of 20 = 1, 2, 4, 5, 10, 20

(g) 18 = 1 × 18

= 2 × 9

= 3 × 6

∴ Factors of 18 = 1, 2, 3, 6, 9, 18

(h) 23 = 1 × 23

∴ Factors of 23 = 1, 23

(i) 36 = 1 × 36

= 2 × 18

= 3 × 12

= 4 × 9

= 6 × 6

∴ Factors of 36 = 1, 2, 3, 4, 6, 9, 12, 18, 36

**Q2: Write first five multiples of :**

**(a) 5**

**(b) 8**

**(c) 9**

Answer:

(a) 5 × 1 = 5,

5 × 2 = 10,

5 × 3 = 15,

5 × 4 = 20,

5 × 5 = 25

∴ First five multiples of 5 are 5, 10, 15, 20, 25.

(b) 8 × 1 = 8,

8 × 2 = 16,

8 × 3 = 24,

8 × 4 = 32,

8 × 5 = 40

∴ First five multiples of 8 are 8, 16, 24, 32, 40.

(c) 9 × 1 = 9,

9 × 2 = 18,

9 × 3 = 27,

9 × 4 = 36,

9 × 5 = 45

∴ First five multiples of 9 are 9, 18, 27, 36, 45.

**Q3: Match the items in column 1 with the items in column 2.**

**Column 1 Column 2**

(i) 35 (a) Multiple of 8

(ii) 15 (b) Multiple of 7

(iii) 16 (c) Multiple of 70

(iv) 20 (d) Factor of 30

(v) 25 (e) Factor of 50

(f) Factor of 20

Answer:

(i) → (b), (c)

(ii) → (d),

(iii) → (a),

(iv) → (f),

(v) → (e)

**Q4: Find all the multiples of 9 upto 100.**

Answer: Multiples of 9 up to 100 are: 9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99

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