Percentage of a quantity

Finding a percentage of an amount by multiplying, using mental shortcuts like 10% and 1%, and expressing one quantity as a percentage of another.

Finding a percentage of an amount

$$\text{percentage} \times \text{amount}, \quad \text{e.g. } 15\% \text{ of } 80 = \frac{15}{100} \times 80 = 12$$

Percentage of an amount

Drag A to change the amount, and the slider to change the percentage.

Example 1●

Sam scored $34$ out of $40$. Write this as a percentage.

$\dfrac{34}{40} \times 100\% = 85\%$

Example 2●●

Write $45$ cents as a percentage of $\$3$.

$\$3 = 300$ cents.

Same units first.

$\dfrac{45}{300} \times 100\% = 15\%$

Flashcards

$10%$ of an amount

Divide by $10$.

$25%$ of 60

$15$

Part as a percentage

$\dfrac{\text{part}}{\text{whole}} \times 100\%$

Practice