Step 1$\Rightarrow$Straight set=$\left \{ A,1,2,3,4,5,6,7,8,9,10 \right \}$ and 1st card can start from any of the element from the set and then continue contiguously,so number of ways we can do this is $\binom{10}{1}= 10$
Step 2$\Rightarrow$There are 4 suits ,so number of ways selecting 1 suit from this 4 is $\binom{4}{1}= 4$
Step 3$\Rightarrow$5 choices(5 cards) are there for this 4 possiblity making it $4^{5}$
Using Product rule $N\left ( E \right )=10*4^{5}$
N(S)=$\binom{52}{5}$
Therefore required probablity=$N\left ( E \right )/N\left ( S \right )$=$10*4^{5}/\binom{52}{5}$