Securing understanding of multiplication with fractions | Maths

Starter quiz

A prime number has exactly ______ factors.

'2' ✓
Which of the following will be less than 8?

${7}\over{5}$ $\times 8$

${8}\times1 {{1} \over {8}}$

${8}\over{9}$ $\times 8$ ✓

${8}\times{36\over38}$ ✓
${1}\over{7}$ × ${1}\over{8}$ is ______ than ${1}\over{6}$ × ${1}\over{8}$ .

'less' ✓
Using this fact, ${8}\over{76}$ × ${36}\over{150}$ = ${144}\over{5700}$ , which of the following are true?

${4}\over{76}$ × ${36}\over{150}$ = ${72}\over{5700}$ ✓

${8}\over{76}$ × ${18}\over{150}$ = ${72}\over{5700}$ ✓

${16}\over{76}$ × ${36}\over{150}$ = ${288}\over{5700}$ ✓

${20}\over{76}$ × ${36}\over{150}$ = ${350}\over{5700}$
Calculate 25 × ${3}\over{5}$ × ${5}\over{6}$ . Give you answer as a mixed number.

${25}\over{2}$

${375}\over{30}$

$12 {{1} \over {2}}$ ✓

$13 {{1} \over {2}}$
Calculate ${28}\over{63}$ × ${105}\over{1155}$ by writing each numerator and denominator as a product of its prime factors.

${2}\over{33}$

${4}\over{33}$

${2}\over{99}$

${4}\over{99}$ ✓

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When multiplying you multiply the numerators together and the denominators together.
Any value can be written as a fraction with one as the denominator.
You can use equivalent fractions to be more efficient.

When multiplying a fraction by an integer multiplying the numerator and denominator by the integer.

If they do this they will have effectively multiplied by 1. Use an example to show you end up with the same fraction that you started with.

Product - A product is the result of two or more numbers multiplied together.
Commutative - An operation is commutative if the values it is operating on can be written in either order without changing the calculation.
Prime factors - Prime factors are the factors of a number that are, themselves, prime.