Cryptology
Modular Arithmetic
Number Theory Proofs
Probability
Number Riddles
100

The algorithm that is used to encrypt information over the internet.

What is the RSA Algorithm?

100

What does it mean to say c = a (mod b)?

c and a both have the same remainder when divided by b.

100

This is the contradictory statement to: "If A then B".

What is "If A then not B".

100

This is defined as the probability that one event occurs has no affect of the probability of another event occurring.

What is an independent event?

100

This is the number of times you can subtract 5 from 25.

What is once?

200

This is the modulus for any Caesar Cipher encryption.

What is 26?

200

This is the solution to 100 (mod 12).


What is 4?

200

This is the contrapositive statement to: If A then B.

If not B, then not A

200

If the probability of getting an A is (7/10) and the probability of catching the bus after class is (4/5), this the probability that both events will happen at the same time.

What is (7/10)*(4/5) = 28/50?

200

What two whole, positive numbers that have a one-digit answer when multiplied and a two-digit answer when added?

What is 1 and 9?
300

This theorem is the basis for the RSA Algorithm. 

What is Fermat's Little Theorem.

300

This is the modulus when you want to find an x that is congruent to the following equations:

x = 4 (mod 7)

x = 5 (mod 3)

What is 21?

300

The definition of a rational number is that a rational number's decimal places can be represented by p/q where p and q must be this mathematical term. (Hint: it was what we used to prove the square root of 2 was irrational).

What is coprime or relatively prime?

300

This is the number of ways someone could arrange 5 backpacks in a row, each with a different color.

What is 5*4*3*2*1?

300

Add me to myself and multiply by 4. Divide me by 8 and you will have me once more. What number am I?

Any number.
400

The phrase "I LOVE NUMBERS" can be encoded when 23(mod 26) is added to each letter to this code.

What is "F ILSB KRJYBOP"?

400

This is one solution for x to 3x = 4 (mod 5)

What is x = 3?

400

Prove by direct proof: 2b^3 + 1 is odd

b = 2k +1

2*(2k+1)^3 + 1

We know (2k+1)^3 will be an integer.

2*integer + 1 = odd number.


400

This is the number of ways to arrange 10 books into 4 different spots on a shelf.

What is 10!/(10-4)! = 10!/6! ?
400

If

12 + 12 = 9

25 + 25 = 49

18 + 18 = 81

What is 29 + 29 = ?

What is (2+9)^2 = 121?

500

This modulus and remainder of the Caesar Cipher will shift "MATH" to "DOHV".

What is letter # + 17(mod 26).

500

This is the general solution to x for the following equation: x + 30 (mod 12) = 1 (mod 12).

What is 19 + 12k where k is an integer?

500

Prove by contradiction: If a and b are integers, the product is odd if and only if a and b are both odd.

Contradictory Statement: If a and b are integers, the product is odd if and only if a and b are both even.

a = 2k1

b = 2k2

a*b = (2k1)*(2k2) = 4(k1*k2) = even

500

If there is a group of 4 girls and 6 boys a 3 members are randomly selected from the group to join a committee, this is the probability of picking 2 girls and one boy from this group.

What is [(4 choose 2)*(6 choose 1)]/(10 choose 3)

500

If 2 = 5

3 = 10

4 = 17

What does 5 = ?

5 = 26