√a x √b =√axb so find 2 numbers that multiple to make the number (1 must be a square number)
√90 can be split into √9 x √10 and √9 is 3 so is 3√10 and the next questions are solved the same
√306 is 3√34
√73 is 3√8
√236 is 2√59
√3600 is 60
√5120 is 8√80