How to Find a Percentage of a Quantity | The Maths Prof

Added: 2026-05-17

[00:00:00][music] >> Hey guys, in this video I'm going to show you how to find percentages. So in our example, we have to find 5% of 70.

[00:00:16]Now working out percentages is just like when you're finding the fraction of a quantity. You have to take the quantity and multiply it with the percentage, okay? So if you like using a calculator and you're allowed to use a calculator in your exam, you can literally just type 5% multiplied by 70 into the calculator and it will give you the correct answer, okay? Just be careful though because 5% is not the same thing as the number five. You must remember to use the percent symbol if you use that method, okay? But if you don't use a calculator, okay, and you need to know how to work this out in your head, what I suggest you do is turn your percentage into a fraction, okay? So when you're writing a percentage, remember it's out of 100. So 5% is the same thing as five out of 100.

[00:01:06]And remember we have to multiply it by the quantity, so we're multiplying by 70 in this question. Okay, so we're multiplying these together. 5 multiplied by 70 is 350, but we also have to divide it by 100.

[00:01:21]And if we divide a number by 100, the decimal point here is going to move two places to the left. So the answer is 3.5.

[00:01:30]And that is 5% of 70.