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  1. Start with the number of U.S. ounces in a U.S. gallon.
  2. Subtract the atomic number for Samarium.
  3. Add the amount of days in February on a leap year.
  4. Multiply this by 6 factorial.
  5. Divide this by pi rounded to the nearest whole.
  6. Divide this by xx+x if x=4
  7. Add xxxxxx if x=y and y = 2z and z=3
  8. Multiply the amount of prime numbers under 20
  9. Add 20 factorial.
  10. Divide this by 1001110001000000000 in the base 10 system (It's in binary there)
  11. Add 30 factorial
  12. Divide this by 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 3 * 5 * 5 * 5 * 5 * 5 * 5 * 5

What is the final answer?

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    $\begingroup$ Hi! Welcome to Puzzling Beta! Please read help center and tour to find out more to create puzzles of high quality, and especially this post: puzzling.stackexchange.com/questions/5880/… As commented by Joe Z., this isn't so much a puzzle as it is a list of instructions. $\endgroup$
    – justhalf
    Commented Apr 9, 2015 at 7:09
  • $\begingroup$ I was going to comment that this doesn't seem much worse than this puzzle with a positive score, but in fact maybe it does. There isn't much to look up that people won't know already (except the Samarium thing), and it's not really very challenging provided you have a big calculator. Maybe it's even more of a maths problem than a maths puzzle - see this meta post. $\endgroup$ Commented Apr 9, 2015 at 8:33

1 Answer 1

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This isn't so much a puzzle as it is a list of instructions to get a secret number, but I'll humour you.


  1. Start with the number of U.S. ounces in a U.S. gallon.

There are 8 ounces in a cup, 2 cups in a pint, 2 pints in a quart, and 4 quarts in a gallon, for a total of 8 × 2 × 2 × 4 = 128 ounces in a gallon.

  1. Subtract the atomic number for Samarium.

Samarium has an atomic number of 62, so our result is 128 - 62 - 66.

  1. Add the amount of days in February on a leap year.

February has 29 days in a leap year, so 66 + 29 = 95.

  1. Multiply this by 6 factorial.

6 factorial is 720, so 95 × 720 is 68400.

  1. Divide this by pi rounded to the nearest whole.

Pi rounded to the nearest whole is 3, so 68400 ÷ 3 = 22800.

  1. Divide this by xx+x if x=4

44 + 4 = 48, and 22800 divided by 48 is 475.

  1. Add xxxxxx if x=y and y = 2z and z=3

If z = 3, then y = 6 and x = 6, so we add 666666 to get 667141.

  1. Multiply the amount of prime numbers under 20

There are eight prime numbers under 20 (2, 3, 5, 7, 11, 13, 17, 19), so we multiply by 8 to get 5337128.

  1. Add 20 factorial.

20 factorial is 2432902008176640000 (Wolfram Alpha), so 5337128 plus that is 2432902008181977128.

  1. Divide this by 1001110001000000000 in the base 10 system (It's in binary there)

1001110001000000000 in base 2 is 320000 in base 10, so our result is 7602818775568.678525.

  1. Add 30 factorial

30 factorial is 265252859812191058636308480000000, so our result is 265252859812191058643911298775568.678525.

  1. Divide this by 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 3 * 5 * 5 * 5 * 5 * 5 * 5 * 5

That product is 480000000, so we divide our above result by that.

What is the final answer?

The very strange number of 552610124608731372174815.20578243474692708333333... with the 3 repeated forever and ever afterwards.


Are you sure you didn't get a few steps wrong there? The number doesn't seem very elegant. Particularly the steps that tell you to add 20 or 30 factorial were a bit strange.

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