Cogito
Grade 6 Math · Chapter 2 · Lesson 3
Finding a Percent of a Number
Ten percent first, then build.
10 problems · about 18 minutes · 6.RP.A.3
What this lesson teaches
The child finds a percent of a quantity using benchmarks and unit rates.
- 10% is the number divided by 10.
- Build other percents from 10%, 5%, and 1%.
- A percent under 100 always gives a smaller answer.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
1 problemReview — Percent as a Rate per Hundred: 17 out of 20 as a percent?
Answer 85
Why 85%.
Warm Up
Straightforward practice. Get the method working first.
4 problemsWhat is 30% of 90?
Answer 27
Why 3 × 9 = 27.
What is 10% of a number?
Answer The number divided by 10.
Why Divide by 10.
What is 10% of 70?
Answer 7
Why Divide by 10.
What is 40% of 50?
Answer 20
Why 10% is 5, four of those.
Build It Up
The same ideas with more to keep track of.
2 problemsWhat is 25% of 64?
Answer 16
Why A quarter.
What is 5% of 200?
Answer 10
Why 10% is 20, halve it.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsThe Sale: What is 20% of 45?
Answer 9
Why 9.
The Tip: What is 15% of 80?
Answer 12
Why 8 + 4 = 12.
The Class: 60% of 25 students walk to school. How many walk?
Answer 15 students
Why 15 students.