Explanation If number is to be divisible by 25, it should be ended with {25,50,75,100)...
So here, the numbers should end with (25 nd 75)
if we take the no. to be ended with 25, the possibities are 4!/2= 24/2= 12
if we take the no. to be ended with 75, the possibities are 4!/2= 24/2= 12
so 12+12=24