Decimals are numbers with a decimal point that show parts of a whole. We use them every day β money ($3.50), measurements (1.5 km), and more!
π Decimal Place Value
| Tens | Ones | . | Tenths | Hundredths | Thousandths |
|---|---|---|---|---|---|
| 10 | 1 | . | 0.1 | 0.01 | 0.001 |
- 1 = one ten (10)
- 5 = five ones (5)
- 3 = three tenths (0.3)
- 4 = four hundredths (0.04)
- 7 = seven thousandths (0.007)
π Decimals & Fractions
- 0.5 = 1/2 (one half)
- 0.25 = 1/4 (one quarter)
- 0.75 = 3/4 (three quarters)
- 0.1 = 1/10 (one tenth)
π Comparing Decimals
- Line up the decimal points
- Compare digit by digit from left to right
- The first different digit tells you which is bigger
Example: 3.45 vs 3.54 β Compare tenths: 4 < 5, so 3.45 < 3.54
π― Rounding Decimals
Look at the digit AFTER the place you're rounding to:
- 0-4 β Round DOWN (keep the same)
- 5-9 β Round UP (add 1)
Example: 3.847 rounded to 1 decimal place = 3.8
βοΈ Activities
0.5, 0.05, 0.55, 0.15
Answer: ___, ___, ___, ___
- 4.67 β ___
- 8.24 β ___
- 12.95 β ___
π©βπ« Teacher Notes
- Mathematics: Number β decimals