one formula which might help you:
sqrt( a * b ) = sqrt( a ) * sqrt( b )
now you have to "smart split" the number "under Sq. Root symbol".
Guest: Simplify the expression: 88 under Sq. Root symbol
88 = 4 * 22
sqrt( 88 ) = sqrt( 4 ) * sqrt( 22 ) = 2 * sqrt( 22 )
sqrt( 108 ) = 6 * sqrt(3)
sqrt( a / b ) = sqrt( a ) / sqrt( b )
Guest: 4/9 uner Sq. Root symbol (Four/Ninths)
sqrt(4/9) = sqrt( 4 ) / sqrt( 9 ) = 2 / 3
sqrt( 100/49 )= 10/7
sqrt( 5/36 )= sqrt(5)/6