95
Finding a fraction of a number
Textbook: Part 3, lesson 95, pp. 81–83
GoalFind 1/n of a number: divide the number by n.
New words
fraction of a number · sonning ulushiequal part · teng bo‘lakwhat is left · qoldidividing · bo‘lish
Explanation
To find a fraction of a number we divide it into that many equal parts. For half we divide by 2, for a third by 3, for a quarter by 4. In general, to find 1/n of a number we divide it by n. For example, 1/4 of 24 is 24 : 4 = 6. To find what is left we subtract the part from the whole.
Worked examples
1/3 of 36 is 36 : 3 = 12. 1/9 of 36 is 36 : 9 = 4.
A class has 28 pupils and 1/4 of them go to the chess club: 28 : 4 = 7 pupils. Those who do not go: 28 − 7 = 21 pupils.
Class activity
“Fraction master”: the teacher names a number and a fraction (for example “1/8 of 40”). Children split counters (pencils, buttons) into equal groups and show one group.
Practice
1
Find 1/6 of 48.
8
2
A school choir has 36 children and half of them are girls. How many girls are in the choir?
18
3
How many centimetres is 1/8 of a ribbon that is 1 m 20 cm long?
15
4
Aziza spent 1/5 of her 6 000 sum on a notebook. How many sum does she have left?
4800
5
1/6 of a rectangle with area 54 cm² is coloured. What is the area of the coloured part in square centimetres?
9