Question 991404
But there are 26 numbers from 1 to 26, not 100. 
With that,
{{{P(5)=1/26}}}
{{{P(15)=1/26}}}
{{{P(5,15)=(1/26)(1/26)=1/676}}} with replacement
{{{P(5,15)=(1/26)(1/25)=1/650}}} without replacement