Percentage = (Part ÷ Whole) × 100
Part = (Percentage ÷ 100) × Whole
Whole = Part ÷ (Percentage ÷ 100)
Percentage increase = ((New value − Original value) ÷ Original value) × 100
Percentage decrease = ((Original value − New value) ÷ Original value) × 100
Percentage change = ((New value − Original value) ÷ Original value) × 100
10% of 50 = (10 ÷ 100) × 50 = 5
25 out of 200 = (25 ÷ 200) × 100 = 12.5%