To increase £50 by 10%, we can calculate 10% of £50 and add the answer.
£50+£5=£55
We could have obtained the same answer by multiplying £50 by
\[1+10\%=1+\frac{10}{100}=1.1\]
This method is especially convenient when an amount increases several times by different percentages.
Suppose £50 is increased in turn by 10%, 15%, 20% and 25% in steps.
To increase by 10% multiply by
\[1+10\%=1+\frac{10}{100}=1.1\]
To increase by 15% multiply by
\[1+15\%=1+\frac{15}{100}=1.15\]
To increase by 20% multiply by
\[1+20\%=1+\frac{10}{100}=1.2\]
To increase by 25% multiply by
\[1+25\%=1+\frac{10}{100}=1.25\]
To increase by 10% then 15% then 20% then 25%, multiply by
