Rounding Calculator
Round numbers to decimal places, significant figures, or nearest values
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📚 Examples, Rules & Help
⚡Quick Examples - Try These Calculations
🔍How It Works
Rounding Rules
Basic Rounding Rule:
• If the digit to be dropped is 5 or greater: round up
• If the digit to be dropped is less than 5: round down
• For negative numbers: apply same rule to absolute value
Significant Figures
What Counts as Significant:
• All non-zero digits: 123 has 3 sig figs
• Zeros between non-zeros: 1005 has 4 sig figs
• Trailing zeros after decimal: 1.20 has 3 sig figs
• Leading zeros don't count: 0.005 has 1 sig fig
Applications
When to Use Rounding:
• Scientific measurements and uncertainty
• Financial calculations and reporting
• Engineering specifications and tolerances
• Statistical analysis and data presentation
🌍Real-World Applications
❓Frequently Asked Questions
When should I round to decimal places vs significant figures?
Decimal places: Best for financial calculations, measurements with fixed precision
Significant figures: Best for scientific calculations, measurements with uncertainty
Example: Money uses decimal places ($1.25), lab measurements use sig figs (12.3 g)
What's the difference between rounding and truncating?
Rounding: Uses the 5-or-greater rule to determine direction
Truncating: Simply cuts off digits without considering their value
Example: 3.14159 rounded to 2 places = 3.14, truncated = 3.14
But 3.14659 rounded = 3.15, truncated = 3.14
How do I handle the number 5 when rounding?
The standard rule is to round 5 up to the next higher number.
Examples:
• 2.5 rounds to 3
• 3.25 rounded to 1 decimal = 3.3
Some contexts use "banker's rounding" (round to even), but standard rounding is more common.
How many significant figures should I use?
Use the precision appropriate for your measurement or calculation:
Measurements: Match your instrument's precision
Calculations: Use the least precise input's significant figures
Final answers: 3-4 significant figures are often appropriate
🎯Common Use Cases
🎓 Educational Applications
- • Math and science homework problems
- • Laboratory report calculations
- • Engineering problem solving
- • Statistics and data analysis projects
💼 Professional Use
- • Financial reporting and accounting
- • Engineering specifications and tolerances
- • Scientific research and publication
- • Quality control and measurements
🔬 Scientific Work
- • Experimental data analysis
- • Measurement uncertainty calculations
- • Chemical concentration calculations
- • Physics problem solving
💰 Financial Calculations
- • Currency rounding for transactions
- • Investment return calculations
- • Tax and accounting computations
- • Budget and expense tracking