Fractions of Amounts Flashcards

All 5 cards in this deck

In a calculation like "$\frac{1}{3}$ of 24", what operation does the word "of" mean?

Multiply: $\frac{1}{3}\times 24=8$.

What are the steps to find a fraction of a quantity?

e.g. $\frac{2}{5}$ of 40

1. Divide by the denominator: $40\div 5=8$
2. Multiply by the numerator: $8\times 2=16$

True or false? To find $\frac{3}{4}$ of an amount you divide by 3 and multiply by 4.

False.

You divide by the denominator (4) and multiply by the numerator (3).

What are the steps to find the whole when you are given a fraction of it?

e.g. $\frac{2}{3}$ of a number is 48

1. Divide by the numerator to get one part: $48\div 2=24$
2. Multiply by the denominator: $24\times 3=72$

The number is 72.

What are the steps to find a fraction of what is left over?

e.g. a 52 litre tank is $\frac{1}{4}$ full — how many more litres fill it?

1. Subtract from 1 to get the fraction left: $1-\frac{1}{4}=\frac{3}{4}$
2. Find that fraction of the amount: $\frac{3}{4}\times 52=39$ litres