Question

Measure the width of a standard sized piece of paper (printer paper works great) in centimeters. Choose the answer that best represents the correct number of significant figures allowed by the ruler and is closest to your measured value.

Answer 1

we have that

the correct number of significant figures allowed by the ruler is 4 (with 2 decimals)

so

that means

the answer is 21.59

because 21.59 has 4 significant figures and 2 decimals