What is the square root of 784?

##28##

-Write down the factors of ##784## and and see if they share the same with the choices. - For example, if you see ##27## and ##29##, you can tell that there is no factor of ##27## or ##29## in 576 since they are prime number and eliminate them. - At this time you verify one by multiplying ##28xx28## to verify.

Recheck:

##28xx28=784##