Compare Decimals
Order and compare decimals using place value.
Compare Decimals
Compare Decimals
What you'll learn
- To order and compare decimals using place value — not just counting digits.
- To compare decimals in money (which item costs more?) and measurement contexts.
- To use number-line reasoning and padding zeros for fair comparison.
- To apply NCERT Math-Magic 5, Chapter 10 strategies for ranking lengths and prices.
Key concepts
Level 1 — Compare from left to right
Verbal: Compare digits in the highest place first; if equal, move to the next place to the right.
Symbolic: To compare 0.6 and 0.59 → tenths: 6 vs 5 → 0.6 > 0.59.
| Pair | Comparison steps | Result |
|---|---|---|
| 3.4 vs 3.38 | Ones equal; tenths 4 > 3 | 3.4 > 3.38 |
| 0.8 vs 0.80 | Pad: 0.80 = 0.8 | Equal |
| 2.05 vs 2.5 | Tenths: 0 < 5 | 2.05 < 2.5 |
NCERT link: Math-Magic 5, Ch 10 — comparing heights (1.45 m vs 1.5 m) and race timings.
Level 2 — Ordering lists and number line
Verbal: On a number line, further right means greater.
Symbolic: Order 0.7, 0.07, 0.707 from smallest: 0.07 < 0.7 < 0.707.
Real-life: Juice A = ₹18.50, Juice B = ₹18.05, Juice C = ₹19.00 → cheapest to costliest: B, A, C.
| Symbol | Meaning | Memory hook |
|---|---|---|
| > | Greater than | Open mouth toward larger number |
| < | Less than | Point toward smaller number |
| = | Equal | Same place values throughout |
Worked example
Arrange in ascending order: 2.5, 2.05, 2.50, 2.15
Step 1 — Pad mentally: 2.50, 2.05, 2.50, 2.15
Step 2 — Compare ones (all 2), then tenths: 0, 1, 5, 5
Step 3 — Order: 2.05 < 2.15 < 2.5 = 2.50
Answer: 2.05, 2.15, 2.5 (or 2.50)
Which is cheaper: ₹45.7 or ₹45.65?
Step 1 — Compare: 45.70 vs 45.65
Step 2 — Tenths: 7 > 6 → 45.7 > 45.65
Answer: ₹45.65 is cheaper by ₹0.05 (5 paise)
Common mistakes
| Mistake | Why it happens | Fix |
|---|---|---|
| 0.9 < 0.45 because 9 < 45 | Comparing digits without place | 0.9 = 0.90 > 0.45 |
| Longer decimal always bigger | Digit-count trap | Compare place by place from the left |
| 2.5 ≠ 2.50 | Thinking trailing zero changes value | Equal — pad zeros for comparison |
| Wrong order in ascending/descending | Mixing directions | Ascending = small → large; check the question word |
Quick check
- Insert <, >, or =: 0.6 ___ 0.59; 3.08 ___ 3.8.
- Order: 1.2, 1.02, 1.22, 1.002 (smallest first).
- Two ribbons: 2.45 m and 2.5 m — which is longer?
- Stretch: A shop lists prices ₹99.9, ₹99.09, ₹99.99. Rank from cheapest to costliest.
Revision tip: Draw a 0 to 1 number line, mark tenths, and place three decimals you find in today's newspaper (fuel price, gold rate, etc.).
Open the Practice tab for graded questions on Compare Decimals.
Key Takeaways (TL;DR)
- What you'll learn
- Key concepts
- Worked example
- Common mistakes
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