All PSAT Math Resources
Example Questions
Example Question #241 : Arithmetic
Find the product.
Since we have one positive and one negative multiple, the resulting product must be negative.
Example Question #1 : How To Subtract Negative Numbers
If x is a negative integer, what else must be a negative integer?
x – (–x)
x² – x
x – x
x²
x – (–x)
By choosing a random negative number, for example: –4, we can input the number into each choice and see if we come out with another negative number. When we put –4 in for x, we would have –4 – (–(–4)) or –4 – 4, which is –8. Plugging in the other options gives a positive answer. You can try other negative numbers, if needed, to confirm this still works.
Example Question #2 : Negative Numbers
–7 – 7= x
–7 – (–7) = y
what are x and y, respectively
y = 0, x = 14
x = –14, y = 0
x = 0, y = 0
x = 14, y = –14
x = –14, y = 14
x = –14, y = 0
x: –7 – 7= –7 + –7 = –14
y: –7 – (–7) = –7 + 7 = 0
when subtracting a negative number, turn it into an addition problem
Example Question #31 : Integers
13
15
16
5
2
16
Subtracting a negative number is just like adding its absolute value.
Example Question #1 : Even / Odd Numbers
Which of the following could represent the sum of 3 consecutive odd integers, given that d is one of the three?
3d – 3
3d + 3
3d + 4
3d – 6
3d – 9
3d – 6
If the largest of the three consecutive odd integers is d, then the three numbers are (in descending order):
d, d – 2, d – 4
This is true because consecutive odd integers always differ by two. Adding the three expressions together, we see that the sum is 3d – 6.
Example Question #1 : How To Add Odd Numbers
, where and are distinct positive integers. Which of the following could be values of and ?
0 and 20
5 and 15
–10 and 30
10 and 10
4 and 5
5 and 15
Since and must be positive, eliminate choices with negative numbers or zero. Since they must be distinct (different), eliminate choices where . This leaves 4 and 5 (which is the only choice that does not add to 20), and the correct answer, 5 and 15.
Example Question #1 : Even / Odd Numbers
The sum of three consecutive odd integers is 93. What is the largest of the integers?
Consecutive odd integers differ by 2. If the smallest integer is x, then
x + (x + 2) + (x + 4) = 93
3x + 6 = 93
3x = 87
x = 29
The three numbers are 29, 31, and 33, the largest of which is 33.
Example Question #1 : Even / Odd Numbers
You are given that are all positive integers. Also, you are given that:
is an odd number. can be even or odd. What is known about the odd/even status of the other four numbers?
and are odd; is even; can be either.
None of the other responses are correct.
, , and are odd; can be either.
and are odd; and are even.
ia odd; and are even; can be either.
and are odd; is even; can be either.
The odd/even status of is not known, so no information can be determined about that of .
is known to be an integer, so is an even integer. Added to odd number , an odd sum is yielded; this is .
is known to be odd, so is also odd. Added to odd number , an even sum is yielded; this is .
is known to be even, so is even. Added to odd number ; an odd sum is yielded; this is .
The numbers known to be odd are and ; the number known to be even is ; nothing is known about .
Example Question #2 : Even / Odd Numbers
You are given that are all positive integers. Also, you are given that:
is an odd number. can be even or odd. What is known about the odd/even status of the other four numbers?
, , , and are even.
None of the other responses are correct.
and are even; and are odd.
and are odd; and are even.
, , , and are odd.
None of the other responses are correct.
A power of an integer takes on the same odd/even status as that integer. Therefore, without knowing the odd/even status of , we do not know that of , and, subsequently, we cannot know that of . As a result, we cannot know the status of any of the other values of the other three variables in the subsequent statements. Therefore, none of the four choices are correct.
Example Question #1 : Even / Odd Numbers
You are given that are all positive integers. Also, you are given that:
You are given that is odd, but you are not told whether is even or odd. What can you tell about whether the values of the other four variables are even or odd?
, , , and are odd.
and are odd; is even; can be either.
and are even; is odd; can be either.
and are odd and and are even.
and are even and and are odd.
and are odd and and are even.
, the product of an even integer and another integer, is even. Therefore, is equal to the sum of an odd number and an even number , and it is odd.
, the product of odd integers, is odd, so , the sum of odd integers and , is even.
, the product of an odd integer and an even integer, is even, so , the sum of an odd integer and even integer , is odd.
, the product of odd integers, is odd, so , the sum of odd integers and , is even.
The correct response is that and are odd and that and are even.