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MAINTAIN + INTERNET = FIREWALL

What is this puzzle?

Solve the addition alphametic puzzle where MAINTAIN + INTERNET = FIREWALL. Each letter represents a unique digit from 0-9. No number starts with zero.

Difficulty: hard · Category: addition · Unique letters: 10

This hard-level addition alphametic puzzle features 10 unique letters (A, E, F, I, L, M, N, R, T, W). In the equation MAINTAIN + INTERNET = FIREWALL, each letter maps to a distinct digit from 0 to 9. The leading letters M and I and F cannot represent zero — this is your first constraint. To solve this efficiently, focus on letters that appear in multiple positions across the equation — these are the most constrained and often the easiest to determine first. This is a challenging puzzle that requires systematic use of carry analysis, parity checking, and elimination. Start by listing all constraints, then methodically eliminate impossible digit assignments.

  • This addition alphametic has 10 unique letters to determine.
  • Leading letters: M, I, F. None of these can be zero.
  • All 10 digits (0–9) are used, one per letter.
  • Start from the rightmost column (units place) and work left, tracking carries between columns.
  • With two addends, each column can produce a carry of at most 1.
  • With many unique letters, use elimination and constraint tracking to narrow down possibilities step by step.

Play this puzzle

MAINTAIN
+
INTERNET
FIREWALL
A=
E=
F=
I=
L=
M=
N=
R=
T=
W=

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