Question

The length of a table is measured by two observers as 2.5m and 2.54m. Which is more accurate and why?

Answer 1

the length of a table is measured by 2 observer as 2.5 m and 2.54 m. 
2.54 m is more accurate as the 2nd observer has considered the value till 2 digits after decimal point whereas the 1st observer has considered only one digit after decimal point.