Into Math Grade 5, Unit 4: Decimals: Place Value, Addition, and Subtraction
In this unit, your child extends place value past the decimal point, learning that each place is worth ten times the place to its right. They read, write, compare, and round decimals to the thousandths, then add and subtract decimals by lining up place values. It follows the fraction units and leads into multiplying and dividing decimals.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 4?
- Explaining that each place is worth ten times the place to its right, so 0.9 is ten times 0.09. Learn more: What each digit is worth, including decimals
- Reading and writing decimals to the thousandths in words and expanded form, and comparing them with <, >, and =. Learn more about reading and writing decimals to thousandths: Reading and writing decimals to thousandths · Learn more about comparing decimals to thousandths
- Rounding decimals to the nearest whole number, tenth, or hundredth, like 4.68 to 4.7, using place value. Learn more: Rounding decimals, like 4.68 to 4.7
- Adding and subtracting decimals to the hundredths by lining up the decimal points and checking with estimates. 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
How many hundredths are in 1 tenth?
- 10
- 1/10
- 100
How you can help
- Compare race times with different numbers of digits, like a 12.48-second run and a 12.5-second run. Ask which is faster and how place value tells you.
- Round prices to the nearest dollar while shopping, then add the rounded amounts for a quick estimate. Compare it with the real total at the register.
- Track distances on a walk or ride, like 1.25 miles one day and 0.8 miles the next. Ask your child to add them and to find the difference.
Where kids can get stuck
- Mixing up direction, so they say the 4 in 0.04 is worth more than the 4 in 0.4.
- Rounding to the wrong place, giving 5 or 4.68 when asked to round 4.68 to the nearest tenth.
- Lining up the last digits instead of the decimal points when adding, so 3.4 + 1.25 gets 1.59 instead of 4.65.
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
- place value
- The value a digit has because of its place in a number.
- decimal
- A number with a decimal point, showing parts of a whole in tenths, hundredths, and smaller.
- tenth
- One of 10 equal parts of a whole, written 0.1.
- hundredth
- One of 100 equal parts of a whole, written 0.01.
- thousandth
- One of 1,000 equal parts of a whole, written 0.001.
- expanded form
- A number written as the sum of each digit's value, like 3 + 0.4 + 0.05.
- round
- To change a number to a nearby, easier number, like 4.68 to 4.7.
- decimal point
- The dot that separates the whole number from the parts of a whole.
Want to help your child master decimal place value?
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 Into Math Grade 5 Unit 4 cover?
Into Math Grade 5 Unit 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.