Learn to compare and order decimals using place value understanding. Master decimal comparison with race times and real-world scenarios.
Scenario: You're timing a 100-meter race! The runners' times are: Alex 12.4 seconds, Sarah 12.35 seconds, and Mike 12.8 seconds. Who finished first, second, and third? How do you determine the order when the times are so close?
This is where decimal comparison skills come in handy! We need to compare decimals by looking at each place value from left to right to determine which is larger or smaller.
Compare decimals by looking at each place value from left to right, starting with the largest place value.
To order decimals, arrange them from smallest to largest (ascending) or largest to smallest (descending).
Ascending: 0.5, 0.05, 0.55 → 0.05, 0.5, 0.55
Descending: 0.5, 0.05, 0.55 → 0.55, 0.5, 0.05
Start by comparing the digits to the left of the decimal point. The number with the larger whole number part is greater.
Example: 3.7 vs 2.9 → 3 > 2, so 3.7 > 2.9
If the whole number parts are equal, compare the tenths place (first digit after the decimal point).
Example: 2.4 vs 2.7 → 4 < 7, so 2.4 < 2.7
If the tenths are also equal, compare the hundredths place (second digit after the decimal point).
Example: 2.45 vs 2.43 → 5 > 3, so 2.45 > 2.43
Order these race times from fastest to slowest:
Sort these decimals from smallest to largest:
1. 0.7 ___ 0.07 (>, <, or =)
2. 2.45 ___ 2.54 (>, <, or =)
3. 1.23 ___ 1.203 (>, <, or =)
4. 0.9 ___ 0.90 (>, <, or =)
5. Order from smallest to largest: 0.6, 0.06, 0.66
6. Order from largest to smallest: 1.5, 1.05, 1.55
7. Order from smallest to largest: 2.3, 2.03, 2.33
8. Order from largest to smallest: 0.8, 0.08, 0.88
9. Which is heavier: 2.5 kg or 2.05 kg?
10. Which is longer: 1.25 m or 1.2 m?
11. Which temperature is higher: 23.5°C or 23.05°C?
12. Which price is lower: $12.99 or $12.9?
Wrong: 0.5 < 0.05 because 0.05 has more digits
Correct: 0.5 > 0.05 because 5 tenths > 5 hundredths
Wrong: 1.23 = 1.203 because both have 1, 2, and 3
Correct: 1.23 > 1.203 because 3 tenths > 0 tenths
Compare decimals by place value from left to right
Start with the largest place value and work your way down
Use number lines to visualize decimal order
Practice with real-world examples like measurements and money