How it works

This calculator helps you determine the number of significant figures in a given number and round it to a specified count. It's a crucial tool for students in chemistry, physics, and other science courses to ensure accurate reporting of measurements.

The Formula

Rules for counting significant figures:
1. Non-zero digits are always significant. 2. Zeros between non-zero digits are significant. 3. Leading zeros (before non-zero digits) are not significant. 4. Trailing zeros are significant only if the number contains a decimal point. Rules for rounding to significant figures:
1. Identify the digit to be rounded. 2. If the next digit is 5 or greater, round up. 3. If the next digit is less than 5, keep the digit as is. 4. Replace digits to the right with zeros (if before decimal) or drop them (if after decimal) to maintain magnitude.

Worked Example

1. Rounding to 3 Significant Figures

   Let's say you have the number 0.004567 and you need to round it to 3 significant figures. 1. First, identify the significant figures: 4, 5, 6, 7. The leading zeros (0.00) are not significant. 2. We need 3 significant figures, so we look at the 4, 5, 6. The next digit is 7. 3. Since 7 is 5 or greater, we round up the last significant digit (6) to 7. 4. The rounded number becomes 0.00457. The trailing 7 is dropped.

Tips, Assumptions & Limitations

• Always consider the context of your measurement when determining significant figures.
• Leading zeros (like in 0.005) are never significant; they just show the decimal place.
• Trailing zeros are significant only if there's a decimal point (e.g., 120. has 3 sig figs, 120 has 2 sig figs).