Classic 'four twos' math puzzle traced to Dirac's general solution from the 1920s
The piece revisits a long-running recreational math puzzle: using exactly four instances of the digit 2 and any mathematical operations to construct any target natural number. It walks through increasingly advanced solutions—from basic arithmetic to exponents, factorials, concatenation tricks, and the Gamma function—before noting that physicist Paul Dirac devised a general method using nested square roots and logarithms that can produce any number, effectively solving the puzzle completely.
GoKawiil's interpretation of the reporting above, not reported fact.
The piece suggests this puzzle has served as an accessible entry point into progressively deeper mathematical concepts, from grade-school arithmetic to complex numbers and special functions. Dirac's general solution illustrates how a seemingly playful problem can connect to serious mathematical reasoning, though the piece frames the fun as continuing even after a 'complete' solution exists, since constrained or elegant solutions remain interesting puzzles in their own right.
- The puzzle asks for any natural number to be built using exactly four 2s and any operations.
- Solutions range from simple arithmetic to factorials, Gamma functions, and complex numbers depending on skill level.
- Paul Dirac reportedly found a general nested-square-root-and-logarithm method that can generate any number, in the 1920s.
Casio fx-991EX ClassWiz Calculator — This puzzle is a great excuse to explore exponents, factorials, and the Gamma function hands-on, and a scientific calculator like this lets you test wild four-2s expressions instantly. It's a handy tool for students or math enthusiasts who want to experiment beyond pencil-and-paper arithmetic.
See Casio fx-991EX ClassWiz Calculator on Amazon → Affiliate link — we may earn a commission on purchases, at no extra cost to you. Product picked by AI based on this article; it is not a tested recommendation.Source: eli.thegreenplace.net, 2026-11-07
Published there as: “Making any integer with four 2s (2025)”
Read the original report → The summary and analysis above are GoKawiil's own, written from reporting by the source above. Facts and quotes belong to the original publisher.