JEE Mains Model Paper 25

LCM of p and q will be r2 , if exponent of r is 2 in at least one of p and q i.e., (0, 2), (2, 0),(1, 2), (2, 1) and (2, 2), so the exponent for r can be selected in 2 × 2 + 1= 5 ways.Similarly, the exponent for s and t can be selected in 2 × 4 + 1 = 9 and 2 × 2 + 1 = 5 ways,respectively. Hence, the total number of selections = 5 × 9 × 5 = 225 ways.