4th grade · Math · Unit 5 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.
Alaska content standards learning standard: 4.NF.6; 4.NF.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
Decimals in Alaska
In the Alaska content standards, this is unit 5 of 15 in 4th grade Math, after Fractions and before Patterns & Tables.
Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.
Source: Alaska Department of Education and Early Development
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
Write 83 hundredths as a decimal.
answer box
0.83
Hint: Hundredths use two places after the decimal point: tenths, then hundredths.
Question 2
What decimal goes where the ? is?
- 9.8
- 9.7
- 10
- 9.9
9.9
Hint: Each small jump is 1 tenth (0.1). Count the jumps from 9.5.
Question 3
Which sign goes in the box?
3.34 3.2
- <
- =
- >
>
Hint: Line up the decimal points. Write both with hundredths (3.20 and 3.34) and compare the ones, then the tenths, then the hundredths.
Question 4
Put the decimals in order from least to greatest.
- 0.82
- 0.46
- 0.98
- 0.12
0.12 → 0.46 → 0.82 → 0.98
Hint: Write them all with hundredths (like 0.4 → 0.40) so they're easier to compare. Then compare the ones, the tenths, then the hundredths.
Question 5
What is 5.3 − 4.9?
5.3 − 4.9 = ?
answer box
0.4
Hint: Line up the decimal points and write both with hundredths: 5.30 − 4.90. Subtract the hundredths, then the tenths, then the ones, regrouping if you need to.
Question 6
What is 7.08 + 2.68?
7.08 + 2.68 = ?
answer box
9.76
Hint: Line up the decimal points. Write both with hundredths (7.08 and 2.68), then add the hundredths, the tenths and the ones. Estimate first: about 7 + 3.