Grades 6-7 · Percentages
35% off $40: find a percent with the 10% trick
0:43 video · Watch on YouTube
35% off a $40 costume saves $14, so you pay $26. Find 10% first by dividing by 10 (10% of 40 is 4), then build the rest: 30% is 3 × 4 = 12 and 5% is half of 4 = 2, and 12 + 2 = 14.
Many children answer $35, reading the percent as dollars. The 10% trick turns any percent into small, friendly steps, and it works for discounts, tips and test questions alike.
The question, solved step by step
A $40 Halloween costume is 35% off. How much do you save, and how much do you pay?
- 10% is easy: divide by 10. 10% of 40 = 4.
- 30% is three lots of 10%: 3 × 4 = 12.
- 5% is half of 10%: half of 4 = 2.
- 35% = 30% + 5% = 12 + 2 = 14. You save $14.
- You pay $40 - $14 = $26.
Answer
You save $14 and pay $26.
The common mistake
Reading 35% as $35. A percent is "out of 100", and 35% is less than half, so the saving on a $40 costume must be less than $20.
Parent tip
Practice 10% first, with prices you see while shopping. Once your child can find 10% in their head, 5%, 20%, 30% and 35% all build from it.
Video transcript
0:00Halloween costume sale! Thirty-five percent off a forty dollar costume. How much do you save?
0:07Max says thirty-five dollars. Hmm, not quite!
0:10Try it together. Three, two, one!
0:13Here's the trick. Ten percent is easy. Ten percent of forty is four.
0:18Thirty percent is three fours, twelve. Five percent is half of four, two.
0:24Twelve plus two is fourteen. You save fourteen dollars, so you pay twenty-six!
0:29Parents, practice ten percent first. Every other percent builds from it.
0:34Subscribe for more! Want one on one help for your child? Book a free math assessment at taleemsquare.com.
Also as a YouTube Short.
Questions parents ask
What is the easiest way to find a percent of a number?
How do you work out 35% off a price?
What grade learns to find a percent of a number?
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