Financial Maths · Ordinary Level
Percentages
Ordinary Level · Part 2 · Tap NEXT to begin
Section 1 of 3
Finding a Percentage
Per cent means out of 100. To find a percentage of an amount, change the $\%$ to a decimal (divide by $100$) and multiply.
The 1% method
$100\% =$ the whole amount, so $1\% = $ amount $\div 100$. Multiply that by the percentage you want. Always round money to 2 decimal places.
Worked example — a simple percentage
Find $12\%$ of €150.
$12\% = 0.12 \times 150 = $ €$18$
or: $1\% = 1.5$, so $12\% = 1.5 \times 12 = $ €$18$
€18
Worked example — a decimal percentage
Find $6.5\%$ of €39.63.
$1\% = 0.3963$
$6.5\% = 0.3963 \times 6.5 = 2.57595$
€2.58 (to 2 d.p.)
You try
Find $17\%$ of €350.
$0.17 \times 350$, or $1\% = 3.50$ then $\times 17$.
$1\% = 3.50$, so $17\% = 3.50 \times 17$
$= $ €$59.50$
€59.50
Section 2 of 3
Percentage Increase
Increase = add on
Work out the increase and add it: amount $+$ increase. Or multiply by $(100 + x)\%$ in one step.
Worked example — increase by 15%
Increase €250 by $15\%$.
Increase $= \tfrac{15}{100} \times 250 = $ €$37.50$
New price $= 250 + 37.50 = $ €$287.50$
or: $115\% = 2.5 \times 115 = $ €$287.50$
€287.50
You try
Increase €574 by $16\%$.
$1\% = 5.74$. Find $16\%$ and add, or go straight to $116\%$.
$16\% = 5.74 \times 16 = $ €$91.84$
$574 + 91.84 = $ €$665.84$
€665.84
Section 3 of 3
Percentage Decrease
Decrease = take off
Work out the decrease and subtract it, or multiply by $(100 - x)\%$.
Worked example — decrease by 5%
Decrease €870 by $5\%$.
$1\% = 8.70$, so $95\% = 8.70 \times 95$
$= $ €$826.50$
€826.50
You try
Decrease €2514.20 by $6.2\%$.
$1\% = 25.142$. Find $6.2\%$ and subtract.
$6.2\% = 25.142 \times 6.2 = $ €$155.88$
$2514.20 - 155.88 = $ €$2358.32$
€2358.32
That’s Part 2.
Finding a percentage, increasing and decreasing by a percentage — always rounding money to 2 decimal places. Next: profit, loss & VAT, then compound interest, tax and foreign exchange.