Other Factors / Multiples - ISEE Upper Level (grades 9-12) Quantitative Reasoning

Card 0 of 20

Question

Which of these numbers is relatively prime with 18?

Answer

For two numbers to be relatively prime, they cannot have any factor in common except for 1. The factors of 18 are 1, 2, 3, 6, 9, and 18.

We can eliminate 32 and 34, since each shares with 18 a factor of 2; we can also eliminate 33 and 39, since each shares with 18 a factor of 3. The factors of 35 are 1, 5, 7, and 35; as can be seen by comparing factors, 18 and 35 only have 1 as a factor, making 35 the correct choice.

Compare your answer with the correct one above

Question

Which of the following is the prime factorization of 333?

Answer

To find the prime factorization, break the number down as a product of factors, then keep doing this until all of the factors are prime.

Compare your answer with the correct one above

Question

What is the sum of all of the factors of 27?

Answer

27 has four factors:

Their sum is .

Compare your answer with the correct one above

Question

Give the prime factorization of 91.

Answer

Both are prime factors so this is the prime factorization.

Compare your answer with the correct one above

Question

Add all of the factors of 30.

Answer

The factors of 30 are 1, 2, 3, 5, 6, 10, 15, and 30. Their sum is

.

Compare your answer with the correct one above

Question

How many factors does 40 have?

Answer

40 has as its factors 1, 2, 4, 5, 8, 10, 20, and 40 - a total of eight factors.

Compare your answer with the correct one above

Question

Which is the greater quantity?

(a) The number of factors of 15

(b) The number of factors of 17

Answer

(a) 15 has four factors, 1, 3, 5, and 15.

(b) 17, as a prime, has two factors, 1 and 17.

Therefore, (a) is greater.

Compare your answer with the correct one above

Question

Which is the greater quantity?

(a) The number of factors of 169

(b) The number of factors of 121

Answer

Each number has only three factors. 121 has 1, 11, and 121 as factors; 169 has 1, 13, and 169 as factors. The answer is that the quantities are equal.

Compare your answer with the correct one above

Question

Which is the greater quantity?

(a) The product of the integers between and inclusive

(b) The sum of the integers between and inclusive

Answer

The quanitites are equal, as both can be demonstrated to be equal to .

(a) One of the integers in the given range is , so one of the factors will be , making the product .

(b) The sum of the numbers will be:

Compare your answer with the correct one above

Question

Which is the greater quantity?

(a) The sum of the factors of

(b) The sum of the factors of

Answer

(a) The factors of are Their sum is

.

(b) The factors of are Their sum is

.

(b) is greater.

Compare your answer with the correct one above

Question

Which is the greater quantity?

(a) The sum of all of the two-digit even numbers

(b) 2,500

Answer

The sum of the integers from to is equal to . We take advantage of the fact that the sum of the even numbers from 10 to 98 is equal to twice the sum of the integers from 5 to 49, as seen here:

Compare your answer with the correct one above

Question

What is the prime factorization of ?

Answer

First make a factor tree for 16. Keep breaking it down until you get all prime numbers (for example: , which then yields ). Then, at the end, remember to factor the variables as well. Since the b term is squared, that means there are two of them. Therefore, the final answer is .

Compare your answer with the correct one above

Question

Which one is greater?

The total number of factors of

Answer

Factors of are:

. So it has factors, which is less than .

Compare your answer with the correct one above

Question

Which one is greater?

number of factors of

Answer

Factors of are:

. So it has factors which is less than .

Compare your answer with the correct one above

Question

Which one is greater?

The sum of all of the factors of

Answer

Factors of are:

. So we can write:

Compare your answer with the correct one above

Question

Which one is the greater quantity:

Sum of the factors of

Sum of the factors of

Answer

Factors of are:

and their summation is:

and the factors of are:

and their summation is:

So is greater than .

Compare your answer with the correct one above

Question

Which one is greater?

The number of factors of

The number of factors of

Answer

has only three factors of

and

also has three factors of

So the number of their factors are the same

Compare your answer with the correct one above

Question

Which one is greater?

The number of factors of

The number of factors of

Answer

The factors of are . So has ten factors.

The factors of are . So has eight factors.

So is greater than .

Compare your answer with the correct one above

Question

If we consider the factors of as a set of numbers, compare the mean and the median of the set.

Answer

Factors of are . So we should compare the mean and the median of the following set of numbers:

The mean of a set of data is given by the sum of the data, divided by the total number of values in the set:

The median is the middle value of a set of data containing an odd number of values which is in this problem. So the mean is greater than the median.

Compare your answer with the correct one above

Question

If we consider the factors of as a set of numbers, compare the mean and the median of the set.

Answer

Factors of are . So we should compare the mean and the median of the following set of numbers:

The mean of a set of data is given by the sum of the data, divided by the total number of values in the set:

The median is the middle value of a set of data containing an odd number of values which is in this problem. So the mean is greater than the median.

Compare your answer with the correct one above

Tap the card to reveal the answer