Wzór: x⋅100% = p%. Przykłady: 1/2 = 1/2 ⋅ 100% = 50%, 1/4 = 1/4 ⋅ 100% = 25%, 0,3 = 0,3 ⋅ 100% = 30%. p/100 = p%. Przykłady: 1/2 = 50/100 = 50%, 1/4 = 25/100 = 25%; 0,3 = 3/10 = 30/100 = 30%