How to calculate percentage of a percentage?

srsly, I can't understand it. can someone help me by giving a step by step procedure on how to solve a problem? Desperately, I'm in need of it.How to calculate percentage of a percentage?
say you are asked to calculate 25% of 40% of 2500

first we calculate 40% of 2500

this is 40/100 * 2500 = 1000



now we calculate 25% of 1000

25/100 * 1000 = 250

so 25% of 40% of 2500 = 250



NOTE the order i followed, first 40 then 25

its always inside to outside!!!How to calculate percentage of a percentage?
Basically to calculate a percentage of a percentage is to look at them as decimals or fractions. For example, 50% of 50%=.5*.5=1/2 * 1/2 = .25=1/4.

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