If a circular piece of tin has a measured radius of 2.6 cm . What is circumference ?

Explanation

r= 2.6cm Circumference of circular disc= `2pi r`
`=2 xx 3.1428 xx 2.6`
Here 2.6 has only 2 significant digits. Hence in the above multiplication `pi` value should be written with `2 + 1= 3` significant figures.
`pi= 3.1428= 3.14`
Circumference `=2 xx 3.14 xx 2.6`
= 16.328
This is to be rounded off to 2 significant digits. Circumference is 16cm.