[X]

Privacy Policy + T&C

We use cookies to personalise our content and ads, and for traffic analysis. Information about your use of our site is shared with our advertising and analytics providers. You also agree to our T&C.

[X]

Common Answers

Have you entered August's Common Answers?

BB Logo Spacer
Spacer
Line
Line

Puzzle - Answer

Start with a number larger than 0, square it, add 4, double, take away 3, times 4 and finally subtract the original number.

If you were now left with 20, what number did you start with?

 [Ref: ZWXM] © Kevin Stone

Answer: 1/8.

If we convert the question to algebra we have:

((n^2 + 4) x 2 - 3) x 4 - n = 20

Expanding the brackets and simplifying gives:

(2n^2 + 8 - 3) x 4 - n = 20

    (2n^2 + 5) x 4 - n = 20

         8n^2 + 20 - n = 20

              8n^2 - n = 0

                    8n = 1

                     n = 1/8

Back to the puzzles...

 

 



This website uses cookies, for more information please view our privacy policy. By using the site you also agree to our terms and conditions.

Line
Line