To find X% of a number, enter: number × X ÷ 100
To calculate what percent one number is of another, enter: part ÷ whole × 100
To increase a number by X%, enter: number × (1 + X ÷ 100)
To decrease a number by X%, enter: number × (1 – X ÷ 100)
To find the 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)