Percentages Flashcards
What is a percentage?
A proportion that shows a number as parts per hundred. It uses the symbol %.
How do you find a% of x?
By converting a% into a/100 and then multiplying it by x.
How do you increase x by a%?
Find a% of x and then add that on.
How do you write a as a percentage of b?
You make the fraction a/b and then you convert it into a decimal before multiplying it by one hundred.
How do you write the percentage change from a to b?
You write the fraction |a-b|/a and then convert it into a percentage.
If you know that b is k% of an unknown, how do you find the unknown?
The unknown will be 100b/k.
How do you work out simple interest?
You calculate the percentage amount of interest that will be added on and multiply it by the number of periods the money will be invested for.
How do you work out compound interest?
You convert the percentage interest into a decimal and then put it to the power of of the number of periods it will be put in for. Then you multiply it by the original amount.
