Work out square numbers from 1 to 20 1 (1x1=1), 4 (2x2=4), 9 (3x3=9), 16 (4x4=16) Probability is 4 out of 20 = 4 / 20, simplified is 1 / 5 (4 into 4 is 1, 4 into 20 is 5) therefore the probability that the number Robin selects randomly is a square of a natural number is 1/5.
