Challenge Response 188

Climbing Steps

If there are seven steps, it is necessary to reach the 7th step, but all other previous steps are optional.

Let's assume that the binary sequence:
0 0 0 1 0 1 1

represents a mode using steps 4, 6 and 7.

To find the total number of ways to climb seven steps, we need to find out how many binary sequences there are using 6 binary digits (since step 7 will always be 1).

We have then 26 = 64 ways to climb the seven steps.

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