Decimals & Percents · Percent of a number · 6.3

Any percent of a number.

Any percent of any number: convert to a decimal and multiply. 35% of 60 = 0.35 × 60 = 21. Estimate with benchmarks to check (a third of 60 ≈ 20).

01 / THE IDEA

See it work.

Watch the method

Percent of a number

35% of 60 = 0.35 × 60 = 21.

1 / 2
35% of 6035\%\text{ of }60
1

Turn the percent into a decimal

35% = 0.35.

35%=0.3535\% = 0.35
2

Multiply by the number

“Of” means multiply.

0.35×60=210.35 \times 60 = 21
02 / YOUR TURN

Practice until it feels automatic.

Your turn

Work it out.

Type a decimal, e.g. 0.75.

streak 0
best 0
… =
— / WHY IT WORKS

The idea underneath.

Convert and multiply

The method never changes: percent → decimal → multiply by the number.

Why it works

35% of 60 is a bit over a third → 21.

03 / WORKED EXAMPLES

From easy to tricky.

EX 1easy

What is 25% of 80?

1

Turn the percent into a decimal

25% = 0.25. 25% = 0.25

2

Multiply by the number

“Of” means multiply. 0.25 × 80 = 20

EX 2medium

What is 40% of 200?

1

Turn the percent into a decimal

40% = 0.4. 40% = 0.4

2

Multiply by the number

“Of” means multiply. 0.4 × 200 = 80

EX 3hard

What is 40% of 20?

1

Turn the percent into a decimal

40% = 0.4. 40% = 0.4

2

Multiply by the number

“Of” means multiply. 0.4 × 20 = 8

04 / COMMON TRAPS

Where students slip.

Trap

Forgetting to convert the percent.

Fix

35% = 0.35 before multiplying.

Trap

Not checking the size.

Fix

Use a benchmark to sanity-check.

05 / QUIZ

Test yourself.

The Test

12 problems across three tiers. Auto-graded on submit. Hints and a full walkthrough on every question. Your work is saved on this device — sign in to keep it across devices.

0/12Answered
How to answerType just the value. Formatting won't trip you up — we ignore spaces, capital letters, commas, and subscript style, so t₁ = 5, d = 3 and t1=5,d=3 both count. For a list of numbers, separate them with commas (e.g. 3, 10, 17).
Core

Core (4)

C1

What is 40% of 120?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.
C2

What is 60% of 40?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.
C3

What is 40% of 180?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.
C4

What is 20% of 60?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.
Apply

Apply (4)

A1

What is 20% of 40?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.
A2

What is 50% of 160?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.
A3

What is 15% of 30?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.
A4

What is 10% of 140?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.
Extension

Extension (4)

E1

What is 60% of 60?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.
E2

What is 75% of 50?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.
E3

What is 25% of 90?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.
E4

What is 10% of 160?

Need a hint?
  • Make the percent a decimal.
  • Multiply, then estimate to check.