Go Math! Grade 5, Chapter 4: Multiply Decimals
In this unit, your child multiplies decimals: by whole numbers, by other decimals, and by 10, 100, and 1,000. Spotting how the digits shift when multiplying by a power of 10, and estimating first, helps them place the decimal point correctly. It builds on adding and subtracting decimals and leads straight into dividing decimals in the next unit.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Chapter 4?
- Spotting how digits shift left when multiplying by powers of 10, so 0.25 × 1,000 = 250. Learn more: Multiplying and dividing by 10, 100, and 1,000
- Multiplying decimals by whole numbers and decimals, like 3.6 × 0.4 = 1.44, and estimating to place the decimal point. Learn more about adding and subtracting decimals to hundredths: Adding and subtracting decimals to hundredths · Learn more about multiplying decimals to hundredths · Learn more about dividing decimals to hundredths
Sample questions to try together
These are real questions from our practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
Amara's family packs rice for a food bank in bags of 1.5 kilograms. How many kilograms of rice are in 10 bags?
- 0.15 kilograms
- 15 kilograms
- 11.5 kilograms
How you can help
- Work out the cost of 3.5 pounds of apples at $2 a pound at the store. Ask your child to estimate first, then find the exact cost, $7.00.
- Ask what 100 sheets of paper weigh if one weighs 0.16 ounces. Let your child see the digits shift to 16 ounces, then try 1,000 sheets, 160 ounces.
- Measure a window or tabletop in meters, like 1.2 by 0.8. Ask your child to multiply for the area, 0.96 square meters, and check it is just under 1.
Where kids can get stuck
- Moving the decimal point the wrong way, so 0.25 × 100 becomes 0.0025 instead of 25.
- Expecting a decimal product to be bigger, so 3.6 × 0.4 = 1.44 looks too small to them.
- Counting decimal places incorrectly, writing 0.5 × 0.7 as 3.5 instead of 0.35.
Practice makes perfect
Bobby's Math Club has practice problems that adapt to your child’s level, each with a detailed explanation and an easy-to-follow video, so your child can build confidence in these skills one step at a time.
Words your child will hear
- product
- What you get when you multiply numbers together.
- factor
- One of the numbers being multiplied, like 6 or 4 in 6 × 4.
- decimal point
- The dot in a number like 4.25 that comes right after the ones place.
- power of 10
- 10, 100, 1,000, and so on: each one is ten times the one before.
- exponent
- A small raised number that tells how many times to multiply the base, like the 3 in 10³.
- estimate
- A close guess found with easier numbers, used to check whether an answer makes sense.
- tenth
- The first place to the right of the decimal point.
- hundredth
- The place two spots to the right of the decimal point.
Want to help your child master decimal multiplication?
In Bobby's Math Club, your child practices these skills at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free.
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Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
Which math standards does Go Math! Grade 5 Chapter 4 cover?
Go Math! Grade 5 Chapter 4 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
For teachers: Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence. Learn how Bobby's Math Club can help your students grow.