can anyone please tell me how to reduce its time limit.
although it passes all the test cases but answer not accepting.

Your code works at a speed O(t * sqrt(n)).
Putting that in the form of numbers, O(10^5 * 10^4), which is O(10^9). The total number of operations you can do in one second is 10^8, that is why it is giving tle.

Answer to the code

ll findMultiple(ll n)
while(n / 5 != 0)
ans += (n / 5);
n /= 5;
return ans;