My dear friend, It is just a simple intelligence question so I follow this pattern.
the answer of this question is 54325.
as 1 = 5
then 2= 25 ( Here you can see 2 in front of the previous result), therefore
3= 3 25 ( write 3 in front of 25)
4= 4 325 ( 4 in front of 325)
so then 5 will equal 5 4325