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usE oF opErator ‘oF’ in Fractions

Pradeep had 18 marbles. He gave 2 of the marbles to his younger brother. How many
3
marbles did he give to his brother?

From this problem, what do we understand?

Here, ‘of’ indicates multiplication. So, we can write the above statement mathematically, as
2 of 18 = × 18 = 2 × 18 = 12 marbles.
2
3 3 3
Example: Evaluate the following.

2
2
( a) of 15 (b) of 9
5 3 14
Solution:
2
2
( a) 2 of 15 = × 15 = 2 × 15 = 6 (b) 2 of 9 = × 9 = 2 × 9 = 3
5 5 5 3 14 3 14 3 × 14 7

practice time 4d

1. Multiply the following:

4
3
( a) by 5 (b) by 5 (c) 20 by 5 (d) 7 by 12
8 7 25 20
2. Find the product in its lowest term.

7
( a) of 2 3 ( b) of 6 3 ( c) 10 × 1 ( d) × 3
6 5 9 8 15 6 9 28

3
3
1
3
2
( e) × × 5 2 ( f) × × 2 2 ( g) × × 1 6 ( h) × × 7
4 6 3 5 6 9 5 4 8 4 5 9
3. Evaluate the following.
4
5
5
( a) of 48 km (b) of 81 kg (c) of 7 ( d) 7 of 4 hours
8 9 7 30 20
1
4. Rajat purchases 2 litres of milk daily. How many litres of milk does he purchase in a
week? 2
1
5. Seema finishes of a task in 1 hour. How much of the task will she finish in
3
1
2 hours?
5
1
6. Nidhi, Kajal, Sonal and Payal each ate of a pizza. How much pizza did
they eat altogether? 8

7. The weight of an object on Earth is 6 times its weight on the Moon. If
3
an object weighs 5 kg on the Moon, how much would it weigh on Earth?
5

Mathematics-5 93