we know that 
The probability of an event is the ratio of the size of the event space to the size of the sample space. 
The size of the sample space is the total number of possible outcomes 
The event space is the number of outcomes in the event you are interested in. 
so 
 P=size of the event space/size of the sample space 
 step 

Find the factors of the number 


In this problem
size of the sample size=
 
 
size of the event space=


therefore
the answer is
The probability is equal to 
