Percentages in Everyday Life
Discounts, tips, and exam scores — calculate percentages in your head.
Lesson
Percent means “per hundred.” 25% of 80 is the same as 25/100 × 80.
Quick tricks: 10% is move the decimal one place left. 5% is half of 10%. 20% is double 10%. Stack these chunks for 15%, 30%, and more without a calculator.
Percent change asks how much something grew or shrank relative to the start. Write (new − old) ÷ old × 100 and watch the sign — negative means a decrease.
Mental percentage skill pairs perfectly with Flash Calculation — holding running totals under time pressure. Try estimating a shop discount before the cashier finishes.
Then confirm with the MathDigits percentage calculator and a short percentages practice quiz so estimation and exact math stay friends.
Practice
Turn this lesson into reps — play a game or open a worksheet.
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What will I learn in “Percentages in Everyday Life”?
Discounts, tips, and exam scores — calculate percentages in your head.
How long does this lesson take?
About 1 minute to read, plus optional practice time.
What should I do after reading?
Try estimating a shop discount, then confirm with the percentage calculator and a short practice quiz.
Is this lesson free?
Yes. All MathDigits Learn guides are free in your browser with no signup required.