Percentage Change: Change/original x 100

Finding Ratio Amounts: 1. Add up the parts 2. Find the amount for 'one' part 3. Multiply the answer of 2 by the amount of parts

Express x as a percentage of y e.g. Give 40p as a percentage of 3.34 (40 / 334) x 100 = 12%

if you want to know an amount before a certain percentage was added you divide the amount by the multiplier of the amount we have at the start

HCF - the biggest number that will divide by all the numbers in the question

The Factors of a number are all the numbers that divide into it

irrational numbers: NEVER ENDING NON RECURRING DECIMAL (e.g. most square and cube roots)