Find a given percent of a quantity.
Free, timed SHSAT practice sets on percent of a number— every question includes a full worked explanation, and there's no account required.
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Percent means "out of 100." To find a percent of a number, change the percent to a decimal (move the decimal point two places left), then multiply.
Mental shortcuts: 10% moves the decimal point one place left, 1% moves it two places, 50% is half and 25% is a quarter. Build other percents from these: 35% is 10% + 10% + 10% + 5%.
The most common trap is a decimal point in the wrong place, which gives an answer 10 times too big or too small (5.2 or 520 instead of 52). Estimate before you pick: 10% of 650 is 65, and 8% is a little less than 10%, so the answer must be a little less than 65.
62% of \(\$43.00\) \(= 62/100 \times 43 = \$26.66\). (Dividing by 10 instead of 100 (\(43 \times 62 \div 10\)) gives $266.60. Finding the price after taking 62% off (\(\$43.00 - \$26.66\)) gives $16.34. Dividing by 1000 instead of 100 gives about $2.67.) 62% of the price is $26.66.
25% of \(\$24.00\) \(= 25/100 \times 24 = \$6.00\). (Dividing by 10 instead of 100 (\(24 \times 25 \div 10\)) gives $60.00. Finding the price after taking 25% off (\(\$24.00 - \$6.00\)) gives $18.00. Dividing by 1000 instead of 100 gives $0.60.) 25% of the price is $6.00.
20% of 645 \(= 20/100 \times 645 = 129\). (Finding the residents who did NOT arrive before 9 a.m. (\(645 - 129\)) gives 516. Subtracting 20 residents instead of 20% (\(645 - 20\)) gives 625. Reading 20% as 20 residents gives 20.) That is 129 residents.