The approximate value of the square root of 285 is ?

The correct option is D 17
${15}^2$ = 225 ,
${16}^2$ = 256 ,
${17}^2$ = 289 ,
${18}^2$ = 324 .

Hence, by observation, we can say that ${16}^2$ < 285 < ${17}^2$.
Since 285 is much closer to 289
( i.e ${17}^2$ ) , so , $\sqrt{285}$ $\approx$ 17.