n(S) = Total number of ways of drawing 2 cards from 52 cards = 52C2.
Let E = event of getting 1 club and 1 diamond.
We know that there are 13 clubs and 13 diamonds in the total 52 cards.
Hence, n(E) = Number of ways of drawing one club from 13 and one diamond from 13 = ¹³C₁ × ¹³C₁ = 13/102
P(E) = n(E)/n(S)
= (¹³C₁ × ¹³C₁) / ⁵²C₂
= 13/102.