Principles of mathematical induction

Let n₀ Є N and let P (n) be a statement for each natural number n ≥ n₀.  Suppose that

• The statement P (n0) is true.
• For all n ≥ n₀, P (K) is true => P (K + 1) is true.

Then P (n) is true for all n ≥ n₀.

Cube:

Sum of the ‘n’ numbers:

Square: