๐ Significant Figures – Concept Builder for Class 8 (IIT Foundation)
๐ What Are Significant Figures?
Significant figures (or significant digits) are the digits in a number that carry meaningful information about the precision of a measurement.
๐ Why Do We Need Significant Figures?
Measurements can never be perfectly exact. Significant figures tell us how accurate a number is.
Example: 5.0 cm (measured with precision) vs 5 cm (a rough estimate).
๐ Rules for Counting Significant Figures
| Rule No. | Rule | Example | Sig. Figures |
|---|---|---|---|
| 1 | All non-zero digits are significant | 567 | 3 |
| 2 | Zeros between non-zero digits are significant | 507 | 3 |
| 3 | Leading zeros are not significant | 0.005 | 1 |
| 4 | Trailing zeros after decimal are significant | 2.300 | 4 |
| 5 | Trailing zeros without decimal are ambiguous | 1500 | 2 (unless written in scientific notation) |
๐งช More Examples
- 0.008 → 1 significant figure
- 3.40 → 3 significant figures
- 7.00 → 3 significant figures
- 5.000 → 4 significant figures
- 3.20 × 105 → 3 significant figures
๐ฌ Scientific Notation Helps!
- 1.50 × 10³ → 3 significant figures
- 1.5 × 10³ → 2 significant figures
๐ซ Common Mistakes to Avoid
- Don’t count leading zeros (e.g., 0.004 has only 1 sig fig)
- Exponents in scientific notation don’t affect sig figs
- Be cautious with trailing zeros in whole numbers (e.g., 400 vs 400.0)
๐ก Pro Tip:
Significant figures reflect how confident you are in your measurement!
๐ Ready to test yourself? Try this interactive quiz on significant figures below!
