Sum of squares of three consecutive nature books____ Give a reason for the square of a natural number!

Sum of squares of three consecutive nature books____ Give a reason for the square of a natural number!

1) All natural numbers can be expressed as one of 3k, 3K + 1, and 3K + 2 (where k is a natural number), so the square of natural numbers can be expressed as: 3K = 9K = 3 (3K), (3K + 1) = 9K + 6K + 1 = 3 (3K + 2K) + 1, (3K + 2) = 9K + 12K + 4 = 3 (3K + 4K +..., and the square of natural numbers can be expressed as: 3K = 9K = 3 (3K), 3K + 1 = 9K + 6K + 1 = 3 (3K + 2K) + 1, (3K + 2) = 9K + 12K + 4 = 3 (3K + 4K +