Instructables

Number Scrabble - The Game (aka: Math Scrabble)

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Step 2: The Rules

  • Except as noted, game play is similar to normal Scrabble
  • On each turn, players must make or add to a valid and correct equation.
  • Players keep 9 tiles in their hand at all times, not 7 as in normal Scrabble
  • Players form valid equations rather than words.
    • example: '3+3=6'
  • You can add to an existing equation on one side or both sides in a single turn.
    • example: you can add to both ends of '3+3=6' in a single turn to make '63+3=66'
  • You may only use one new '=' sign per turn
  • Order of operation:  The game will function correctly as long as you agree beforehand on the order of operation.  You can play with either "standard math" (ie, multiply preceeds plus unrelated to the written order), or  "strict left-to-right evaluation".
    • Square and Square-root operators apply only to the immediately preceding or following number
    • There is no implied multiplication
  • Equations can have multiple equal parts.
    • example: '2x2=1+3=4=5-1'
  • Redundant equations are valid
    • example: '1-1+1-1=0=0+0'
  • The '-' may be used either as an operator or before a number indicate its sign.
    • example: '-3=5-8'
    • example: '3=-5--8'
  • You may not use leading '+' signs or leading '0' in front of a number
  • You may not string together arbitrary symbols
    • example: '3+xx4==12' is NOT valid.
  • In normal scrabble, you can place one word alongside another if they create a valid cross-word.  Here, a 2-character sequence can never be an equation so this generally is not possible.  As an optional rule, you may choose to allow placing alongside when only numbers are formed as the cross-words, but you still need to connect to an existing equation some other way.
  • As an optional rule, you may choose to disallow the following "Identity" equation fragments:
    • "x1"   example:  you could not turn '3+4=7' to '3+4=7x1'
    • "+0" and "-0".   example:  you could not turn '3+4=7' to '3+4=7+0'
    • I recommend allowing these when playing in a learning scenario, but disallowing them with experienced players as you get into tedious '2+2=4+0+0+0x1x1' situations.