Fractions · Multiply · 7.1

Multiply across.

To multiply fractions, multiply the numerators together and the denominators together — no common denominator needed. Then simplify.

01 / THE IDEA

See it work.

Watch the method

Multiply across

2/3 × 4/5 = 8/15.

1 / 1
23×45\frac{2}{3} \times \frac{4}{5}
1

Multiply across

Multiply the tops, multiply the bottoms.

2×43×5=815\frac{2\times4}{3\times5} = \frac{8}{15}
02 / YOUR TURN

Practice until it feels automatic.

Your turn

Work it out.

Type a fraction like 3/4 or 1 1/2.

streak 0
best 0
… =
— / WHY IT WORKS

The idea underneath.

Across, not LCD

Multiplication needs no common denominator. Multiply tops, multiply bottoms, simplify.

Why it works

A part of a part: two-thirds of four-fifths.

03 / WORKED EXAMPLES

From easy to tricky.

EX 1easy

Multiply 2/5 × 1/4

1

Multiply across

Multiply the tops, multiply the bottoms. \frac{2\times1}{5\times4} = 2/20

2

Simplify

Reduce to lowest terms. 1/10

EX 2medium

Multiply 2/3 × 1/2

1

Multiply across

Multiply the tops, multiply the bottoms. \frac{2\times1}{3\times2} = 2/6

2

Simplify

Reduce to lowest terms. 1/3

EX 3hard

Multiply 1/2 × 2/4

1

Multiply across

Multiply the tops, multiply the bottoms. \frac{1\times2}{2\times4} = 2/8

2

Simplify

Reduce to lowest terms. 1/4

04 / COMMON TRAPS

Where students slip.

Trap

Looking for an LCD (that’s for adding).

Fix

Just multiply across.

Trap

Cross-multiplying instead.

Fix

Tops × tops, bottoms × bottoms.

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

Multiply 2/5 × 1/4

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.
C2

Multiply 3/5 × 1/3

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.
C3

Multiply 2/6 × 1/2

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.
C4

Multiply 1/5 × 3/4

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.
Apply

Apply (4)

A1

Multiply 2/3 × 1/2

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.
A2

Multiply 2/4 × 1/3

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.
A3

Multiply 2/5 × 5/6

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.
A4

Multiply 4/5 × 1/5

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.
Extension

Extension (4)

E1

Multiply 1/2 × 2/4

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.
E2

Multiply 4/5 × 4/5

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.
E3

Multiply 2/3 × 1/6

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.
E4

Multiply 1/2 × 4/6

Need a hint?
  • Multiply the numerators.
  • Multiply the denominators; simplify.