Page 34 - SM Class 5 Inner.cdr

30 30

5 6 2 15

3 2 3 5

So, 30 = 5 × 3 × 2 So, 30 = 2 × 3 × 5

E xercise 3.3

1. Complete these factor trees :
a. b.
48 72

6 12

So 48 = __________________ So 72 = __________________

2. Solve the following :
a. 56 = 8 × 7 = _____ × _____ × 7 = _____ × _____ × _____ × 7
b. 84 = 12 × 7 = _____ × _____ × 7 = _____ × _____ × _____ × 7

3 Find the prime factors of these numbers by suitable method :
a. 40 b. 85 c. 210 d. 240
e. 32 f. 35 g. 248 h. 125

i. 48 j. 99 k. 132 l. 320
m. 30 n. 720 o. 576 p. 784

Highest Common Factor (H.C.F)

Let us consider the factors (divisors) of three numbers 18, 24, 30.
All factors of 18 : 1, 2, 3, 6, 9, 18
All factors of 24 : 1, 2, 3, 4, 6, 8, 12, 24

All factors of 30 : 1, 2, 3, 5, 6, 10, 15, 30
So, the common factor / divisor of the three numbers are 1, 2, 3, 6.
Among them 6 is the greatest. So, 6 is the highest common factor or H.C.F of 18,
24 and 30. The other name of divisor is factor.

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Mathematics In Focus - 5