Here, the answer is “divide the previous value by 5.”
You can make sure:
125/5 = 25
25/5 = 5
5/5 = 1
1/5 = 1/5
1/5 / 5 = 1/5 x 1/5 = 1/25.
So, we checked and made sure that each number divided by 5 equaled the number below, and confirmed this rule!
Hope this helps! :)