To find X% of a number, enter: number × X ÷ 100
To increase a number by X%, enter: number + (number × X ÷ 100)
To decrease a number by X%, enter: number – (number × X ÷ 100)
To find what percent one number is of another, enter: (part ÷ whole) × 100
To find percentage change, enter: ((new – old) ÷ old) × 100
To find the original number after a percentage increase, enter: final ÷ (1 + X ÷ 100)
To find the original number after a percentage decrease, enter: final ÷ (1 – X ÷ 100)
To calculate a discount price, enter: original price – (original price × discount ÷ 100)
To calculate tax, enter: price + (price × tax rate ÷ 100)
To calculate tip, enter: bill × tip rate ÷ 100