Lesson Worksheet: Mental Multiplication: Doubling and Halving Mathematics

In this worksheet, we will practice using doubling and halving to multiply two numbers.

Q1:

Olivia knows a strategy to multiply by making easier calculations with the same answer.

Use her strategy to find the missing numbers.

Q2:

Multiplying by 2 and 10 is easy!

Let’s rewrite this expression to make it easier.

Which of these is equal to 14×5?

  • A6×10
  • B7×10
  • C10×10
  • D12×10

What is 14×5?

Q3:

Which of the following expressions has the same value as 5×120?

  • A10×60
  • B10×120
  • C10×240
  • D5×60

What is 5×120?

Q4:

Benjamin wants to calculate 15×16. He decides to change the expression to make easier to evaluate without a calculator. If Benjamin doubles 15 to get 30, what should he do to 16?

  • AIt should be halved to 8.
  • BIt should be doubled to 32.
  • CIt should stay the same.
  • DIt should be divided by 4.

What is 15×16?

Q5:

Madison wants to calculate 18×50 without a calculator. To make the calculation easier, she doubles one of the numbers to be 100 and halves the other. What is Madison’s new calculation?

  • A9×50
  • B18×100
  • C6×100
  • D9×100

What is the answer to her calculation?

Q6:

A pack of colors contains 18 coloring pencils. How many coloring pencils are there in 15 packs?

Q7:

A box of honey jars contains 12 jars. How many jars are there in 25 boxes?

Q8:

Isabella is thinking of two numbers. She wants to multiply them mentally, so she doubles one of them to be 30 and halves the other to be 6. What are the two numbers?

  • A16 and 12
  • B15 and 6
  • C15 and 12
  • D30 and 12
  • E30 and 6

Q9:

Jackson, Benjamin, and Liam want to rewrite the multiplication sentence 16×25 using doubling and halving.

Jackson rewrote it as 16×50, Benjamin rewrote it as 8×25, and Liam rewrote it as 8×50.

Rewrite the multiplication sentence yourself, using doubling and halving, and decide who got the right answer.

  • ALiam
  • BBenjamin
  • CJackson

What is the answer to 16×25?

Q10:

Use the doubling and halving strategy to simplify the following multiplication: 25×12.

  • A25×24
  • B25×6
  • C50×24
  • D50×6
  • E50×12

What is the answer to 25×12?

This lesson includes 19 additional questions and 200 additional question variations for subscribers.

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