If 45% of a number is 36, what is the number?

4 Answers
Feb 14, 2017

Number is #80#

Explanation:

As #45%# of a number is #36#,

#45%xx"Number"=36#

or #45/100xx"Number"=36#

or #45/100xx100/45xx"Number"=36xx100/45#

or #cancel45^1/cancel100^1xxcancel100^1/cancel45^1xx"Number"=cancel36^4xx100/cancel45^5#

or #"Number"=(4xxcancel100^20)/(cancel5^1)#

or #"Number"=80#

Feb 14, 2017

#80#

Explanation:

Let the number be #x#

#45%# of #x=36#

#45%# of #x# can also be written as #45% xx x#

#45/100 xx x=36#

#0.45x=36#

#x=36/0.45.#

#x=80#

check:

#:.45% xx 80#

#:.cancel45^9/cancel100^20 xx 80#

#:.9/cancel20^1 xx cancel80^4/1#

#:.9 xx 4=36#

Feb 16, 2017

The number is #80#

Explanation:

Percentage questions can always be done by a direct proportion method, which is the same as using equivalent fractions.

In this case we are told that 36 is #45%# of a certain number. The number itself would represent #100%#

If we use #x# for the number, we have:

#36/45 = x/100" "larr# "If 36 is 45%, how much is #100%?#"

#45x = 36xx100" "larr# cross multiply

#x = (36xx100)/45#

#x = 80#

This method is particularly useful with reverse percentages.

Jun 1, 2017

The number is 80!

Explanation:

Whenever I come across these kind of questions, I use a formula. #x# will represent the number because we don't know the number yet. For this case, the formula would be,
#x##\cdot##45/100##=##36#.

The value of #x# will be the answer. So let's start!

#x##\cdot##45/100##=##36#

#x##=##36##\cdot##100/45# (Leave #x# on one side)

#x##=##cancel36^4/1##\cdot##100/cancel45^5# (Multiply)

#x##=##400/5# (Simplify)

#x##=##80#

Did you know that in mathematics, of means #times# and/or #*#! So #45%# of #80# is,

#45/100##times##80#!

Let's check if the answer is correct!

#45/100##times##80/1#

#=##45/cancel100^5##times##cancel80^4/1#

#=##180/5#

#=##36#

I learned how to type the multiplication sign (dot) here! That's one source, and my other source is my brain!
Now since we checked the answer, we know that #80# is correct!
I hope that helps and that you understood it!

All the best,
Moksha :D