Significant Figures - Introduction

Description:

Number of figures which are important, their count (in numbers) is known as significant figures.

For example,

• If the distance between Delhi to London is specified as 5000km, then there is only one significant figure which is 5 and,

• If the distance between Delhi to London is specified as 5430km, then there are three significant figure which are 5, 4 and 3. Similarly,

• If the distance between Delhi to London is specified as 5432km, then there are four significant figure which are 5, 4, 3 and 2.

In any number or measurement last digit of all important is uncertain while the rest are certain.

For example,

• In the measurement of 5432, the digits 5, 4 and 3 are certain while 2 is uncertain.

• In the measurement of 5430, the digit 5 and 4 are certain while 3 is uncertain.

• In the measurement of 5400, the digit 5 is certain while 4 is uncertain.

Rules for significant figures – Whole number

• All the non-zero digits are significant.
• The trailing zero(s) in a number are not significant.
• All the zeros between two non-zero digits are significant.

Example

Rules for significant figures – Decimal number

• All the non-zero digits are significant.

• All the zeros between two non-zero digits are significant.

• The zero(s) on the right of decimal point but to the left of the first non-zero digit are not significant.

• The trailing zero(s) in a number with a decimal point are significant.

Example