Maths % Question - Anyone help please!

[CornishTeaTime]

£87,000 = 40%

What is 100%?

Divide by 40 then multiply by 100

Correct.

217500

One solution.

Another would be divide by 0.4

I divided by 4 to get 10% then added a 0.

217500

Or divide by 4 (to find 10%) and multiply by 10 (to get 100%) of course.

However imo, explaining it as divide by 40 (to find 1%) and then multiply by 100 (to get 100%) has the beauty that it us relatively clear where the numbers have come from.

'Add a 0'
Multiply by 10!

£217500.00

I do it in my head by dividing by 4 to get 10% and then adding a 0 but if I have a calculator then it’s divide by 0.4.

I have no idea how it is actually taught now though. Probably something entirely different!

Well an easier way is if 87,000 is 40% then 87,000 divided by 4 gives you 10% which is 21,750 and this times by 10 is 217,500

so 100% is 217,500

quad erat demonstrandum

£217,500 is what I get too.

If 87k = 40%
87 x 2 is 80% = 174k
87/2 is 20% = 43500k

so 174+43500
= 217500

Ask Siri

You're a teacher, aren't you? We get hammered for saying "Add a 0" instead of "multiply by 10"!

Not a teacher, maths degree! (But with 2 DD for whom maths does not come naturally, so need clear explanations).

Remember to do the "in your head check" of 40% is less than half, so the answer is going to be more than double... has saved me from giving stupid answers on many occasions.

But yep agree with the others divide by 40 multiply by 100.

£217,500

If I was doing it my head and not asking SIRI I'd double it then add half of the original number
I'd have to do it carefully but would be confident of getting the right answer