Percentage formula: (part ÷ whole) × 100
Find part: part = (percentage ÷ 100) × whole
Find whole: whole = part ÷ (percentage ÷ 100)
Convert decimal to percentage: decimal × 100
Convert fraction to percentage: (numerator ÷ denominator) × 100
Percentage change: [(new − old) ÷ old] × 100
Percentage difference: |a − b| ÷ ((a + b) ÷ 2) × 100
Markup percentage: (price − cost) ÷ cost × 100
Discount percentage: (original − sale) ÷ original × 100