Significant figures (sig figs) are a way to express the precision of a number, particularly in measurements. They indicate which digits in a number are meaningful in terms of accuracy and reliability. Here’s a quick guide to the rules for significant figures:

Rules for Significant Figures:

1. Non-zero digits are always significant.
   Example: 123.45 has 5 significant figures.

2. Zeros between non-zero digits are significant.
   Example: 1002 has 4 significant figures.

3. Leading zeros (zeros to the left of the first non-zero digit) are not significant.
   Example: 0.0025 has 2 significant figures.

4. Trailing zeros in a decimal number are significant.
   Example: 2.500 has 4 significant figures.

5. Trailing zeros in a whole number without a decimal point are not necessarily significant.
   Example: 1500 may have 2, 3, or 4 significant figures depending on the context.

Examples of Correct Significant Figures:

• 456.789 → 6 sig figs.
• 0.00750 → 3 sig figs.
• 1000 → Ambiguous without a decimal; could be 1, 2, 3, or 4 sig figs.
• 1000.0 → 5 sig figs.

Would you like more details or examples about significant figures, or do you have a specific number you’d like checked for significant figures? Here are some follow-up questions:

1. How do significant figures affect calculations in scientific measurements?
2. What are the rules for rounding numbers to a certain number of significant figures?
3. How do significant figures apply to addition and subtraction operations?
4. What is the impact of significant figures in multiplication and division?
5. How do significant figures affect reporting of measurement uncertainty?

Tip: Always check the context of the measurement when determining the significance of trailing zeros; use scientific notation if precision needs to be explicitly shown.