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Here are some tips for Odd or Even Theory, which aligns with Florida state standards:

Odd or Even Theory



To review odd and even numbers, see here.

Addition Subtraction Multiplication
even + even = even even - even = even even * even = even
even + odd = odd even - odd = odd even * odd = even
odd + even = odd odd - even = odd odd * even = even
odd + odd = even odd - odd = even odd * odd = odd

Here is an easier way to think about this.


Example 1: Addition and Subtraction of 3 numbers

Is the resulting number odd or even?
25160 + 35516 - 31337

Rewrite the equation in terms of odd or even, then solve.
25160 + 35516 - 31337  
even + even - odd  
even + even - odd Solve the first part
even - odd even + even = even
odd even - odd = odd
The resulting answer is odd.


Example 2: Addition and multiplication of 3 numbers

Is the resulting number odd or even?
18425 × 29531 + 15309

Rewrite the equation in terms of odd or even, then solve.
18425 × 29531 + 15309  
odd × odd + odd  
odd × odd + odd Solve the first part
odd + odd odd × odd = odd
even odd + odd = even
The resulting answer is even.

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