The total number of digits that are counted while performing a measurement, are called significant figures or significant numbers. In a measured number, all the digits are certain except the last digit. The last digit which is uncertain in a measured number is called estimated digit. In the measurement 543.1267 inches, the last digit 7 is estimated digit. While taking into account the total number of significant figures, we count all the certain digits plus the estimated digit. Therefore, the number 543.1267 has 7 significant figures.
