4th grade · Math · Unit 9 of 15
Decimals
Tenths, hundredths, add and subtract
What your child practices
Tenths and hundredths as decimals, linking them to fractions, placing and comparing them on number lines, and adding and subtracting decimals by lining up the decimal points.
Oregon State Standards learning standard: 4.NF.C.6; 4.NF.C.7 · decimal notation for tenths and hundredths, and comparing decimals
How we explain it
Children can open this short lesson before they practice.
- Tenths: 0.1 is one of ten equal parts. Hundredths: 0.01.
- A decimal point separates wholes from parts.
- Line up the decimal points to add and subtract.
Example: What is 3.3 + 3.5? Line up the points. Tenths: 3 + 5 = 8. Ones: 3 + 3 = 6. Answer 6.8. Answer: 6.8
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
What is 9.8 − 5.7?
9.8 − 5.7 = ?
answer box
4.1
Hint: Line up the decimal points and write both with hundredths: 9.80 − 5.70. Subtract the hundredths, then the tenths, then the ones, regrouping if you need to.
Question 2
In 3.52, what is the value of the digit 2?
3.52
- 2 tens
- 2 hundredths
- 2 ones
- 2 tenths
2 hundredths
Hint: After the decimal point, the first place is tenths and the second place is hundredths.
Question 3
What is 1.62 + 2.97?
1.62 + 2.97 = ?
answer box
4.59
Hint: Line up the decimal points. Write both with hundredths (1.62 and 2.97), then add the hundredths, the tenths and the ones. Estimate first: about 2 + 3.
Question 4
Write 17 hundredths as a decimal.
answer box
0.17
Hint: Hundredths use two places after the decimal point: tenths, then hundredths.
Question 5
Which sign goes in the box?
2.09 2.9
- <
- =
- >
<
Hint: Line up the decimal points. Write both with hundredths (2.90 and 2.09) and compare the ones, then the tenths, then the hundredths.
Question 6
Each bar is 1 whole. What decimal shows the shaded part?
answer box
1.9
Hint: Each bar has 10 equal parts, so each part is 1 tenth (0.1). 1 full bar is 1 whole. Count the shaded tenths in the last bar: 9.