Significant figures are the number of digits in a value, often a measurement, that contribute to the degree of accuracy of the value.

Significant figures are important to show the precision of your answer.

**Formula to express a number in significant figures.**

- For a number without a decimal, you start counting for significant figures on the first non-zero digit from your left.
- Zeroes in between two non-zero digits are significant.
- All non-zero digits are significant.
- Right-end zeros in a number with a decimal point are significant.

**Example:**

Express 45 to 4 significant figures.

To express 45 to 4 significant figures we will need to put a decimal after 5 and then add two zeros as we have been told that the right-end zeros in a number with a decimal point are significant.

Therefore, we will have 45.00.