Answer
Probability = $\frac{10240}{2598960}$ $\approx$ 0.00394
Work Step by Step
Ways to select 5 cards = $C$(52,5) = 2598960
To form a straight we need to have 5 cards in any of the following order
A,2,3,4,5
2,3,4,5,6
...
.
10,J,Q,K,A
10 ways
and each card can belong to any of the 4 suit
Hence ways to form a straight = 10$\times$$4^{5}$ =10$\times$1024 = 10240
Probability = $\frac{10240}{2598960}$ $\approx$ 0.00394
