Writing equations for multiplicative comparison

Mathematics · Multiplication & Division · ages 9-10

Name ______________________ Date ____________

A red ribbon is 7 cm. A blue ribbon is 3 times as long. How long is the blue ribbon?
- 18 cm
- 24 cm
- 21 cm
- 10 cm
A red ribbon is 7 cm long. A blue ribbon is 3 times as long. How long is the blue ribbon in centimetres?
Answer: ______________
Tom has 5 apples. Maya has 3 times as many. Which equation finds Maya's apples (m)?
- 3 x 5 = m
- 3 + 5 = m
- 3 x m = 5
In the equation 4 x n = 36, n stands for an unknown number we need to find.
Circle one: True False
Sam read 5 times as many books as Lily. Lily read 4 books. Which equation and answer shows how many Sam read?
- 5 x 4 = s, s = 20
- 5 + 4 = s, s = 9
- s x 4 = 5, s = 1
Tom has 9 marbles. Sarah has 4 times as many. How many does Sarah have?
- 36
- 13
- 32
- 45
36 is 4 times a number. What is the number?
Answer: ______________
A blue ribbon is 3 times as long as a red ribbon that is 7 cm. How long is the blue ribbon?
Answer: ______________
A ribbon is 6 times as long as a 4 cm string. A student wrote 6 + 4 = r for the ribbon's length r. What mistake did they make?
- They multiplied instead of added; the correct length is 10 cm
- The equation is correct
- They added instead of multiplied; the correct length is 24 cm
A number multiplied by 7 gives 84. What is the number?
Answer: ______________

Answer key

For grown-ups. Fold this page away before handing over the rest.

21 cm · 3 times 7 cm is 21 cm.
21 · 3 x 7 = 21, so the blue ribbon is 21 cm.
3 x 5 = m · '3 times as many' means multiply: 3 x 5 = m, so Maya has 15 apples.
True · n is a symbol holding the place of the missing number until we solve for it.
5 x 4 = s, s = 20 · '5 times as many' means multiply: 5 x 4 = 20 books.
36 · 4 x 9 = 36.
9 · 36 / 4 = 9.
21 · 3 x 7 = 21, so the blue ribbon is 21 cm long.
They added instead of multiplied; the correct length is 24 cm · '6 times as long' needs multiplication, not addition. 6 x 4 = 24 cm.
12 · 84 / 7 = 12.