Mathematics · Grades 9–10
Percentages · Formula sheet
Rules, conditions and small examples in one printable reference.
Remember this
Find the original whole
Divide by the percentage as a decimal, not by the whole-number percent.
whole = part ÷ (p/100)
392 ÷ 0.4 = 980
Successive percentage changes
Apply each percentage to the value at that stage.
final = initial × (1 + p/100) × (1 − q/100)
7400 × 1.2 × 0.9 = 7992
Repeated percentage growth
Use the decimal growth rate; assume the same rate each period.
A = P(1 + r)ⁿ
4900 × 1.25² = 7656.25
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.