Rounding decimals, like 4.68 to 4.7
In 5th grade, children learn to round decimals to any place, like 4.68 to the nearest tenth, using place value to decide which nearby number is closer.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
Try these with your child
These are real questions from our 5th grade 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 swam one length of the pool in 18.6 seconds. What is her time to the nearest whole second?
- 20 seconds
- 18 seconds
- 19 seconds
Why this matters
Rounding gives your child the power to estimate, and estimating is how they will catch their own mistakes. It means knowing $3.459 a gallon is about $3.46, or that 4.68 + 2.1 should be close to 7. Your child will lean on that habit to check decimal answers this year and in middle school, where measurement, money, and percentages all come with digits past the decimal point.
Where kids can get stuck
- Rounding to the wrong place, giving 5 or 4.68 for 4.68 to the nearest tenth instead of 4.7.
- Stumbling when rounding carries over, writing 2.10 or 2.9 for 2.97 to the nearest tenth instead of 3.0.
- Looking at every digit to the right, so the final 9 in 3.149 makes them round up to 3.2 instead of 3.1.
How you can help
- Round grocery prices while shopping: $2.68 is about $3, $5.12 is about $5. Add the rounded prices as you go and compare the estimate with the real total at the register.
- Look at the car's trip meter, which often shows tenths of a mile. Ask your child to round the reading, like 23.6 miles, to the nearest whole mile and explain why.
- Draw a simple number line on paper from 4.6 to 4.7 and ask your child to mark where 4.68 would be. Ask which end it is closer to and what that means for rounding.
Bobby's Math Club offers free practice that grows with your child.
Questions parents ask
Why is my child learning to round decimals with a number line?
A number line shows what rounding really means: finding the closest friendly number. When your child sees that 4.68 sits nearer to 4.7 than to 4.6, the answer makes sense instead of following a rule blindly. That picture also helps with tricky cases, such as 2.97 rounding up to 3.0. Teachers use it so rounding stays connected to the size of numbers.
Why does 2.97 round to 3.0 and not 3?
Both are the same amount. When rounding to the nearest tenth, the answer is written as 3.0 to show it was rounded to the tenths place. If the question asked for the nearest whole number, 3 would be the right way to write it. Your child's teacher may ask for the zero so the precision of the answer is clear.
When will my child use decimal rounding in real life?
Rounding comes up whenever an exact number is not needed: estimating a grocery bill, reading a thermometer, describing a distance, or checking a calculator answer. In school, your child will use it to check decimal addition, subtraction, multiplication, and division later this year. A quick estimate catches answers that are far too large or too small.
Make learning math fun
Bobby's Math Club turns 5th grade math practice into something fun to do together.
- Free, unlimited practice for every child in your family
- Practice that starts where your child is and grows with them
- Hints when they are stuck, and a celebration when it clicks
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.
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Join the clubNote for teachers: This skill is covered by Common Core math standard 5.NBT.A.4: “Use place value understanding to round decimals to any place.” Learn how Bobby's Math Club can help your students grow. (Common Core 5.NBT.4)