Page 70 - ICSE Math 6

THINK SMART

1. A number which lies between 50 and 55 is divisible by 3 and is a product of two prime numbers.
Find the number.

2. The product of two different prime numbers is an odd number. State the following statements as
true or false? Also, give reasons to support your answer.

(i) One of the prime numbers is 2.
(ii) The product is more than 10.

(iii) The product is completely divisible by 2.
Individual Activity

Objective: Finding factors of a number using activity method
Material required: Cardboard, a pair of scissors, a pencil

Let’s find factors of a number, say 10.
Step 1: Cut 10 equal squares of appropriate size from a cardboard.

Step 2: Arrange the 10 squares in all possible ways to form a rectangle or a square.
(i)

(ii) (iii) (iv)

Observation: We observe that Fig. (i) has 1 row, Fig. (ii) has 2 rows, Fig. (iii) has 5 rows
and Fig. (iv) has 10 rows.

Inference: Number of rows in each arrangement are the factors of 10. Therefore,
factors of 10 are 1, 2, 5 and 10.
Verification: 1 is a factor of 10  10 ÷ 1 = 10
2 is a factor of 10  10 ÷ 2 = 5
5 is a factor of 10  10 ÷ 5 = 2
10 is a factor of 10  10 ÷ 10 = 1

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