All GRE Math Resources
Example Questions
Example Question #1 : How To Divide Odd Numbers
Solve for :
To solve, divide both sides of the equation by :
As a check, if you divide an odd number by another odd number, your result should be odd.
Example Question #3 : How To Divide Odd Numbers
Solve for :
To solve, isolate your variable by dividing both sides of the equation by :
Example Question #4 : How To Divide Odd Numbers
Solve for :
To solve, first isolate your variable by dividing both sides of the equation by :
As a check, if you divide an odd number by another odd number, your result should be odd.
Example Question #101 : Integers
Solve for :
To solve, divide both sides of the equation by :
As a check, if you divide an odd number by another odd number, your result should be odd.
Example Question #1 : How To Multiply Odd Numbers
If and are both odd integers, which of the following is not necessarily odd?
With many questions like this, it might be easier to plug in numbers rather than dealing with theoretical variables. However, given that this question asks for the expression that is not always even or odd but only not necessarily odd, the theoretical route might be our only choice.
Therefore, our best approach is to simply analyze each answer choice.
: Since is odd, is also odd, since and odd number multiplied by an odd number yields an odd product. Since is also odd, multiplying it by will again yield an odd product, so this expression is always odd.
: Since is odd, multiplying it by 2 will yield an even number. Subtracting this number from will also give an odd result, since an odd number minus an even number gives an odd number. Therefore, this answer is also always odd.
: Since both numbers are odd, their product will also always be odd.
: Since is odd, multiplying it by 2 will give an even number. Since is odd, subtracting it from our even number will give an odd number, since an even number minus and odd number is always odd. Therefore, this answer will always be odd.
: Since both numbers are odd, there sum will be even. However, dividing an even number by another even number (2 in our case) does not always produce an even or an odd number. For example, 5 and 7 are both odd. Their sum, 12, is even. Dividing by 2 gives 6, an even number. However, 5 and 9 are also both odd. Their sum, 14, is even, but dividing by 2 gives 7, an odd number. Therefore, this expression isn't necessarily always odd or always even, and is therefore our answer.
Example Question #2 : How To Multiply Odd Numbers
Theodore has jelly beans. Portia has three times that amount. Harvey has five times as many as she does. What is the total count of jelly beans in the whole group?
To find the answer to this question, calculate the total jelly beans for each person:
Portia: * <Theodore's count of jelly beans>, which is or
Harvey: * <Portia's count of jelly beans>, which is or
So, the total is:
(Do not forget that you need those original for Theodore!)
Example Question #1 : How To Multiply Odd Numbers
Assume and are both odd whole numbers.
What is a possible solution for ?
When two odd whole numbers are multipliedd, they will equal an odd whole number. The only answer that fits the requirements of being an odd and a whole number is since it comes from or .
Example Question #21 : Even / Odd Numbers
If is even, and is odd. Which of the following must be odd?
To solve, pick numbers to represent and . Let and . Now try each of the equations given:
.
Only works and is thus our answer.
Example Question #2 : How To Multiply Even Numbers
is even
is even
Quantity A:
The remainder of
Quantity B:
1
The relationship between the quantities cannot be determined.
Quantity A is larger.
The two quantities are equal.
Quantity B is larger.
Quantity B is larger.
Begin by considering our options. For , it is either the case that:
is even and is odd, or,
is even and is even, or,
is odd and is even
Now, for , it is either the case that:
and are even, or,
and are odd
Now, for , it cannot be the case that both are odd. This means that the only viable option for is the case when both are even.
Therefore, must be even, meaning that the remainder of must be .
Therefore, quantity B is larger.
Example Question #1 : How To Multiply Even Numbers
is even
is even
Therefore, which of the following must be true about ?
It could be either even or odd.
It must be odd.
It must be even.
It could be either even or odd.
Recall that when you multiply by an even number, you get an even product.
Therefore, we know the following from the first statement:
is even or is even or both and are even.
For the second, we know this:
Since is even, therefore, can be either even or odd. (Regardless of what it is, we can get an even value for .)
Based on all this data, we can tell nothing necessarily about . If is even, then is even, even if is odd. However, if is odd while is even, then will be even.