*P = 1 + (2 · 3) + (4 · 5 · 6) + (7 · 8 · 9 · 10) + (11 · 12 · 13 · 14 · 15) + …*

Starting with 1, the first term, we can add as many terms as we wish.

How many terms should we add such that P is a perfect number?

Hint
What values can the last digit of a perfect square
have?
Can we find a way to determine the last digit of P?

Check your answer

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