Codebusters - Cryptarithm
EditType: Inquiry
Divisions: B, C
Participants: Up to 3
Approx. Time: 50 minutes
Allowed Resources: Writing utensils; up to three Class I or Class II calculators. No external notes. Supervisor provides scratch paper and reference sheet.
Cryptarithm
A cryptarithm is a mathematical puzzle where letters represent unique digits in an arithmetic equation. The goal is to find the digit-to-letter mapping that makes the equation valid.
How to Solve
- Analyze the equation: Look at the structure of the addition/subtraction problem
- Use the numeric example: The puzzle provides a solved numeric version to help you understand the letter-to-digit mapping
- Apply logical constraints:
- Each letter represents a unique digit (0-9)
- Leading letters cannot be zero
- Column-wise addition must hold with carries
- Map letters to digits: Use the provided grid to assign digits to letters
- Decode the message: Use your mapping to decode the number strings into words
Example
Given the cryptarithm:
E A T
+ T H A T
---------
A P P L E
With the numeric example:
8 1 9
+ 9 2 1 9
---------
1 0 0 3 8
Solution Process:
- From the numeric example: E=8, A=1, T=9, H=2, P=0, L=3
- Verify the addition: 819 + 9219 = 10038 ✓
- Decode the digit groups: 2 8 1 9 → H E A T, 9 2 8 → T H E, 0 3 1 9 8 → P L A T E
- Final answer: "HEAT THE PLATE"
Tips
- Start with the rightmost column and work leftward
- Pay attention to carries between columns
- Use the hint to verify your decoded message makes sense
- Remember that leading letters cannot be zero