All GMAT Math Resources
Example Questions
Example Question #7 : Understanding Real Numbers
If and are composite integers, which of the following can be prime?
None of these can be prime.
so this is a composite number for all and .
is by definition a composite number.
the product of 2 numbers.
This leaves just . For a number to be prime, it must be odd (except for 2) so we need to have either or be odd (but not both). The first composite odd number is 9. . The smallest composite number is 4. .
is a prime number.
So the answer is
Example Question #1 : Understanding Real Numbers
If is a real number, which of the following CANNOT be a value for x?
122
-122
-3
3
125
3
The definition of the set of real numbers is the set of all numbers that can fit into a/b where a and b are both integers and b does not equal 0.
So, since we see a fraction here, we know a non-real number occurs if the denominator is 0. Therefore we can find where the denominator is 0 by setting x-3 =0 and solving for x. In this case, x=3 would create a non-real number. Thus our answer is that x CANNOT be 3 for our expression to be a real number.
Example Question #1 : Understanding Real Numbers
Let be the product of integers from 18 to 33, inclusive. If , how many more unique prime factors does have than ?
Not enough information given.
Greater than
This question does not require any calculation. Given that 32 (an even number) is a factor of , then 2 must be a prime factor. If is then multiplied by 2 (to get ) then has no additional unique prime factors (its only additional prime factor, 2, is NOT unique).
Example Question #2 : Real Numbers
If are both negative, then could NOT be equal to....
is negative and is positive
Therefore, the solution cannot be negative.
Example Question #411 : Arithmetic
If is a real number, which one of these cannot be a value of ?
For the expression to be defined, the denominator needs to be different from 0. Therefore:
So the correct answer is 2.
Example Question #1961 : Problem Solving Questions
If , and , and , what can we say for sure about ?
is positive
is negative
None of the other answers.
None of the other answers.
To show the other answers aren't always true, we need to choose 2 numbers that satisfy the given inequalities but also contradict each answer one-by-one.
Let this choice shows that sometimes , which rules out the answers , is negative, and
Now Let , this will still satisfy the given inequalities, but now . This means that the answer " is positive" isn't always true either.
Example Question #412 : Arithmetic
Which of the following is equal to the sum of thirty-three one-thousandths and three hundred three ten-thousandths?
Six hundred thirty-three ten-thousandths
Three hundred thirty-six ten-thousandths
Three hundred sixty-six ten-thousandths
Six hundred six ten-thousandths
Six hundred three ten-thousandths
Six hundred thirty-three ten-thousandths
The one-thousandths and ten-thousandths places are the third places and the fourth places, respectively, to the right of the decimal point. Therefore:
Thirty-three one-thousandths =
Three hundred three ten-thousandths =
Add:
The last nonzero digit ends at the ten-thousandths place, so this is , or
six hundred thirty-three ten-thousandths.
Example Question #1961 : Gmat Quantitative Reasoning
Which of the following is equal to 0.0407?
Four hundred seven ten-thousandths
Four hundred seventy ten-thousandths
Four hundred seven one-thousandths
Forty-seven ten-thousandths
Four hundred seventy one-thousandths
Four hundred seven ten-thousandths
The last nonzero digit is located in the fourth place right of the decimal point - the ten-thousandths place. Put the number, without decimal point or leading zeroes, over 10,000. This number is , or four hundred seven ten-thousandths.
Example Question #12 : Understanding Real Numbers
Which of the following is equal to three one-hundredths subtracted from one fourth?
Twenty-three one-hundredths
Thirty-seven one-hundredths
Five one-hundredths
Twenty-two one-hundredths
Forty-seven one-hundredths
Twenty-two one-hundredths
The one-hundredths place is the second place to the right of the decimal point; therefore, three one-hundredths is equal to 0.03. One fourth can be converted to decimal form as follows:
,
which is twenty-five one-hundredths, or 0.25. Subtract:
,
or twenty-two one-hundredths.
Example Question #15 : Understanding Real Numbers
Order from least to greatest.
We can find each in terms of .
In ascending order, the numbers are:
The correct choice is .