What is 67.5% of 80?

Feb 12, 2017

$54$

Explanation:

Multiply 80 with 67.5% in decimal form, which is $\frac{67.5}{100} \text{ or } 0.675 .$

So we now have:

$80 \times 0.675 = 54$

Feb 12, 2017

54

Explanation:

The % symbol is like a unit of measurement that is worth $\frac{1}{100}$

So  67.5%" is the same as "67.5xx1/100 = 67.5/100

Consider the word 'of' in 65% of 80 as being the same as multiply

As an example: 3 of 78 is the same as $78 + 78 + 78 \to 3 \times 78$

So 67.6% of 80 -> 67.5%xx80 -> 67.5/100xx80

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Let me introduce you to a trick to work this out without using a calculator.

Write as $67.5 \times \frac{80}{100}$

$67.5 \times \frac{8 \times 10}{100}$

$67.5 \times \frac{8}{10}$

8 is the same as $2 \times 2 \times 2$

First doubling of 67.5 = 135.0
Second doubling = 270
Third doubling = 540

Now we have:

$\frac{540}{10} = 54$
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Check by calculator: $\frac{67.5}{100} \times 80 = 54$

$\textcolor{b r o w n}{\text{Sometimes the numbers do not lend themselves to this type of approach}}$