Decimal Operations with Base-Ten Blocks
See decimals as physical blocks. A flat equals 1, a rod equals 0.1, and a small cube equals 0.01. Add, subtract, multiply, and divide by combining and splitting the blocks.
Choose Mode
Choose Operation
Try These Examples
First Number1.24
Flat = 1Rod = 0.1Cube = 0.01
Ones (1)
Tenths (2)
Hundredths (4)
Second Number0.38
Flat = 1Rod = 0.1Cube = 0.01
Tenths (3)
Hundredths (8)
1.24 + 0.38
Decimal Reference
Place Value with Decimals
Each place is 10 times the place to its right.
- Ones (1) = 10 tenths
- Tenths (0.1) = 10 hundredths
- Hundredths (0.01) = smallest here
1.35 = 1 one + 3 tenths + 5 hundredths
Regrouping with Decimals
When adding and the hundredths column reaches 10, regroup:
- 10 hundredths = 1 tenth
- 10 tenths = 1 one
- Same as whole-number carrying, just smaller units
Multiplying Decimals
When multiplying by a whole number, think of repeated addition:
- 1.2 × 3 = 1.2 + 1.2 + 1.2 = 3.6
- Count decimal places in each factor
- The product has the same total decimal places
Dividing Decimals
To divide by a decimal, convert to an equivalent problem with whole numbers:
- 1.5 ÷ 0.5 = 15 ÷ 5 = 3
- Multiply both numbers by 10 or 100
- Then divide as with whole numbers
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