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x and y are prime numbers and x+y=18

Quantity A

xy

Quantity B

70


a and b are primes, a+b=12.

Quantity A

b

Quantity B

8


When the product of four prime numbers a, b, c and d is divided by 77, the result is a multiple of 5. When the product of these four prime numbers is divided by 7, the result could be?

Indicate all such numbers.

Quantity A

The number of prime numbers divisible by 13

Quantity B

The number of prime numbers divisible by 2


Quantity A

The number of prime numbers that are divisible by 9

Quantity B

The number of prime numbers that are divisible by 19


$$p$$ and $$n$$ are positive integers less than 30. $$p$$ is a prime number, while $$n$$ is not a prime number.

Which of the following CANNOT be the sum of $$n$$ and $$p$$?

Indicate all such numbers.
K is a prime number.

Quantity A

The greatest prime factor of 40K

Quantity B

The greatest prime factor of 39K


K is a prime number

Quantity A

The greatest prime factor of 49K

Quantity B

The greatest prime factor of 50K


What is the greatest prime factor of 510?
N=$$11^{2}$$*$$13^{3}$$*15

What is the greatest prime factor of N?
What is the greatest prime divisor of $$3^{100}$$- $$3^{97}$$?
n is an even integer.

Quantity A

The number of prime factors of n

Quantity B

The number of prime factors of $$\frac{n}{2}$$


n is a prime number greater than 5

Quantity A

The number of different prime factors of 2n

Quantity B

The number of different prime factors of $$n^{2}$$


How many integers from 1 to 900 inclusive have exactly 3 positive divisors?
In the game of Dubblefud, red chips, blue chips and green chips are each worth 2, 4 and 5 points respectively. In a certain selection of chips, the product of each point value of the chips is 16,000. If the number of blue chips in this selection equals the number of green chips, how many red chips are in the selection?
For any n, nj means the product of all the positive even integers before n

For example, 18j=18*16*--*2

What is the greatest prime factor of 22j+20j?
For every positive even integer n, the function h(n) is defined to be the product of all the even integers from 2 to n, inclusive. If p is the smallest prime factor of h(100)+1, then p is?
Let S be the set of all positive integers n such that $$n^{2}$$ is a multiple of both 24 and 108. Which of the following integers are divisors of every integer n in S?

Indicate all such integers.
In a certain medical group, Dr. Schwartz schedules appointments to begin 30 minutes apart, Dr. Ramirez schedules appointments to begin 25 minutes apart, and Dr. Wu schedules appointments to begin 50 minutes apart. All three doctors schedule their first appointments to begin at 8:00 in the morning, which are followed by their successive appointments throughout the day without breaks. Other than at 8:00 in the morning, at what times before 1:30 in the afternoon do all three doctors schedule their appointments to begin at the same time?

Indicate all such times
In a factory, machine A operates on a cycle of 20 hours of work followed by 4 hours of rest, and machine B operates on a cycle of 40 hours of work followed by 8 hours of rest. Last week, the two machines began their respective cycles at 12 noon on Monday and continued until 12 noon on the following Saturday. On which days during that time period was there a time when both machines were at rest?

Indicate all such days.

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