**Important Concepts and Formulas**

1. Per cent means per hundred or for
every hundred.

3. To convert a fraction into a per
cent, multiply the fraction by 100.

5. To convert a decimal into a per cent,
shift the decimal point two places to the right.

6. To convert a per cent into a
fraction, divide it by 100 after removing the symbol of %.

7. Increase = Increased value – Original
value.

8. Percentage increase =
(Increase/Original value) × 100% and increased value = (100% + increase %) ×
original value.

9. Decrease = Original value – Decreased
value.

10. Percentage decrease =
(Decrease/Original value) × 100% and decreased value = (100% – decrease %) ×
original value.

12. Profit% = (Profit/C.P.) × 100 and
Loss% = (Loss/C.P.) × 100.

14. Rate per cent = (SI × 100)/(P × T)

15. Time = (SI × 100)/(P × R)

16. Principal = (SI × 100)/(R × T)