On the Subject of Digit String

Terror has arrived in town, for some of your digits... are actually a sign!

  • An eight-digit number is displayed in the bottom display screen. One or more of these digits must be replaced with a mathematical sign.

  • Starting with the first character in the bomb’s serial number, if that character appears multiple times in the serial number, use the Repeat row in List B, otherwise use the row associated with that character.

  • If any number indicated by that condition is found in the displayed number, and replacing the number would NOT result in the sign being either before or after all of the remaining digits, that number should be replaced with a sign. If there are multiple such numbers in the string, use the first applicable instance. Use Table A to determine which sign to use. If a number was replaced, stop and evaluate what you have, otherwise, continue with the next serial number character.

  • If none of the characters’ conditions caused a sign to replace a number, replace the Xth digit of the displayed number with a plus sign, where X is the number of different serial number characters plus one (A00AA0 would count as 2 different characters).

  • Once you have replaced the digit(s) with a sign, evaluate what you get, then type the answer in with the keypad.

  • Use the C button to clear the display and the Submit button to submit your answer. If the answer is correct, the module will be disarmed, otherwise, a strike will be given.

Table A

Serial Number Character Used Sign to Use
1st Times
2nd Greater Than*
3rd Plus
4th Less Than*
5th Times
6th Plus

*Note: For the Greater Than and Less Than inequalities, if the statement evaluates to true, enter 1, otherwise enter 0.

List B: The Rules

  • 0: A three-digit multiple* of 100.
  • 1: A two-digit multiple* of 13.
  • 2: Three even digits in a row.
  • 3: 33, 66, or 99.
  • 4: 65, 16, 47, 73, or 90.
  • 5: A five-digit sequence where the first through fourth digits are different, and the fifth digit is the same as the first.
  • 6: Three consecutive digits that add up to exactly 6.
  • 7: Two consecutive digits with a difference of 7.
  • 8: A three-digit sequence made up of just 2s, 4s, and 8s.
  • 9: Two consecutive digits with a sum of 9.
  • A: A five-digit sequence with no 0s, and where every digit is different.
  • B: A three-digit sequence starting in 1 and ending in 2.
  • C: Three consecutive digits 7 or greater.
  • D: A four-digit sequence where each digit is greater than the one before it.
  • E: Three consecutive digits that add up to exactly 13.
  • F: Four consecutive odd digits.
  • G: Two consecutive digits, the second is at least 3 higher than the first.
  • H: A 7 or 9, followed by an even digit.
  • I: Three consecutive digits, exactly two are 1 and/or 7.
  • J: A three-digit sequence which uses exactly three digits out of 2, 3, 5, and 9.
  • K: A two-digit multiple* of 15.
  • L: Four consecutive digits which add up to exactly 14.
  • M: A four digit number from 5930 to 6075, inclusive.
  • N: Two consecutive digits that are the same.
  • O: A five digit sequence where each digit is either even or 7.
  • P: A 2 or 4, followed by an odd digit.
  • Q: Three consecutive digits which add up to 23 or more.
  • R: Two consecutive digits, both in the bomb’s serial number.
  • S: A four-digit sequence where each digit is less than the one before it.
  • T: Four consecutive digits which add up to either more than 28 or less than 8.
  • U: Three consecutive digits, the first and third match.
  • V: Three consecutive digits from 0 to 2.
  • W: Four consecutive even digits.
  • X: A three-digit number from 395 to 411, inclusive.
  • Y: Five consecutive digits without a 3 or 6.
  • Z: Three consecutive digits, at least two of which are 2 and/or 5.
  • Repeat: (Current serial number position) times 12 or 15.
* 0 is considered a multiple of every number.