No winners for November Math Mania

1. I'm thinking of a number. If I add a half, a fourth, and a ninth of it together, I get 62. What's my number?

Answer: 72

So, 62 is thirty-one thirty-sixths of my mystery number. This can be translated into a simple equation:

2. I'm thinking of another number.

The number is:

Not a multiple of 3.
The product of two primes.
Less than .
Greater than twice the square root of 625.
Not a multiple of 2.

Answer: 55. Clues two and three tell me that the number must be between 50 and 64. After I eliminate all of the multiples of 2 and 3, I'm left with 53, 55, 59, and 61. My number must be 55, since it is the only number that is the product of two primes ( 5 and 11). The other numbers are already prime, thus the products of only 1 and themselves.

3. You guessed it! I'm thinking of yet another number. To help you figure it out, I've given you several clues:

The number is not an odd number.
It has exactly four factors.
If you reverse the digits a prime number is formed.
The sum of the digits is a two-digit prime number.
The number is less than the square root of .
One of the digits is a square number.

Answer: 74. As in the previous problem, work through the clues to narrow down possibilities until you arrive at the answer.

4. Last time, I promise! Use the clues to find my number.

It's greater than and less than .
is one of its factors.
It is a multiple of 13.

Answer: 1950

5. O.K., I lied. One more…

Now I'm thinking of a telephone number.

Each digit is different.
The product of the sixth* and seventh numbers equals the third number.
The fourth, eighth, ninth, and tenth numbers are multiples of 3.
The sum of the fourth and sixth numbers equals the sum of the fifth and eighth numbers.
The second, third, sixth, and seventh numbers are powers of 2.
The first, fifth, seventh, and tenth numbers are prime.

*When I refer to numbers as first, second, third, etc. I'm counting from the left.

Answer: (518) 974-2603