Number Play

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Parity refers to the property of a number being either even or odd. Even numbers can be arranged in pairs without any leftovers, while odd numbers have one leftover when arranged in pairs.

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The sum of two even numbers is always even. This is because even numbers can be arranged in pairs, and when you combine pairs, the result can still be arranged in pairs without leftovers.

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The sum of two odd numbers is always even. Each odd number has one leftover, so two odd numbers have two leftovers, which can form one complete pair, making the sum even.

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The sum of an even number and an odd number is always odd. The even number can be arranged in pairs, but the odd number has one leftover, making the total sum have one leftover (odd).

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No, it's impossible. When you add any odd number of odd numbers (like 5), the result is always odd. Since 30 is even, it cannot be the sum of 5 odd numbers.

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The sum of any two consecutive numbers is always odd. This is because consecutive numbers alternate between even and odd, so one will be even and the other odd, making their sum odd.

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A magic square is a square grid of numbers where each row, each column, and each diagonal adds up to the same number, called the magic sum.

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The magic sum must be 15. Since the sum of all numbers 1-9 is 45, and there are 3 rows that must have equal sums, each row must sum to 45 ÷ 3 = 15.