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# What is the area of the cross section of the wire up to approximate significant figures if the radius of a uniform wire is 0.021 cms. The value of $\pi$ is given to be 3.142.

The area $= \pi r^2 =3.142 \times 0.021^2 = 0.00138562\;cm^2$
Since there are only two significant digits in the radius, the area must also be rounded off to two digits, hence the Area with the appropriate rounding off $= 0.0014\;cm^2$