Odd and Even Numbers
Even numbers are numbers that are divisible by 2 with
no remainder. Remember that zero is included within
this definition.
Even Numbers: . . . , –6, –4, –2, 0, 2, 4,
6, . . .
Odd numbers are numbers that, when divided by 2,
leave a remainder of 1.
Odd Numbers: . . . , –5, –3, –1, 1, 3, 5,
. . .
Operations and Odd and Even Numbers
For the SAT, you have to know how odd and even
numbers act when they’re added, subtracted, multiplied, and divided.
The chart below shows addition, subtraction, and multiplication
because multiplication and division are the same in terms of odd
and even.
| Addition |
|
Subtraction |
|
Multiplication |
| Even + Even =
Even |
|
Even – Even =
Even |
|
Even × Even = Even |
| Odd + Odd = Even |
|
Odd – Odd = Even |
|
Odd × Odd = Odd |
| Even + Odd = Odd |
|
Even – Odd = Odd |
|
Even × Odd = Even |
If you know how odd and even numbers act when put through
any of the four operations, you have a leg up in using the process
of elimination. If the numbers in the answer choices are both odd
and even, you should be able to use the rules of odd and even numbers
to figure out if the answer you’re looking for is odd or even. So even
if you don’t know the exact value of the answer you’re looking for,
you should be able to eliminate half of the answers based on whether
they’re odd or even.
