Math Practice Online: MathScore.com

Math Practice Online > free > lessons > California > 3rd grade > Odd or Even Theory

If your child needs math practice, click here.

For sample problems, click here.
Here are some tips for Odd or Even Theory, which aligns with California 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.

Copyright Accurate Learning Systems Corporation 2008.
MathScore is a registered trademark.