Saturday, September 4, 2010

Maths Problem Answer

Here is the question again:

There are eight doors in a row. Behind each door is a number. Each number is less than 20. No two numbers are the same, and the numbers on the doors are in order.

• three of the numbers are prime numbers
• two of the numbers are square numbers
• two of the numbers are multiples of 5
• five of the numbers are even
• three is a factor of two of the numbers
• there is a run of two consecutive numbers, and another run of four consecutive numbers.
• the numbers sum to 93
What are the numbers on the doors?

How did I do it?
I used a spreadsheet, Exel

I tried to satisfy the 4 consecutive numbers first 
Then the 2 conscutive numbers




And here is the answer:

2, 4, 10, 11, 15, 16, 17, 18
It all equals 93

2,  11, 17 are the prime numbers
4, 16 are the square numbers
10, 5 are multiples of 5
2, 4, 10, 16, 18 are all the even numbers
15, 18 are factors of 3
10, 11 are the two consecutive numbers
15, 16, 17, 18 are the four consecutive numbers

3 comments:

  1. Gosh I thought I had a comment there - BUT IT WAS ME!! sob sob

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  2. I wonder who will comment first!! . . . . other than me!! LOL

    ReplyDelete