A percentage is a number out of . 50/100 = 1/2, so % = 1/2. 25/100 = 1/4, so % = 1/4. 10/100 = 1/10, so % = 1/10. 50% is a half so, to find 50% of an amount, you it or divide by . To find 10% of an amount you divide by . To find one quantity as a percentage of another: the first quantity by the second: first/second then the answer by 100%: first/second × 100% If an amount is increased, the new amount is than 100%. If an amount is decreased, the new amount is than 100%.