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You would need 25 blocks to make a 5 step up and down staircase. I figured this out by drawing a diagram which you can see below. I think the rule is that if you whant he same number of steps on both side of the staircase, you must multiply it by itself. So if you wanted a 3 step up and down staircase you could do 3 times 3. This can also be written as 3 squared. I found this rule by drawing diagrams of 3 and 4 step up and staircases. You can see the diagrams below.