## four fours problemUsing arithmetic combinations of four 4's express all the numbers from 1 to 100. For example, 1 = 44/44 and 2 = (4 × 4)/(4 + 4). The problem was first presented in The Schoolmaster's Assistant: Being a Compendium
of Arithmetic Both Practical and Theoretical (first edition c. 1744),
a popular textbook by the English schoolteacher and cleric Thomas Dilworth
(d. 1780). Operations and symbols that are allowed include the four arithmetic operations (+, × , -, /), concatenation (e.g. the use of 44), decimal points (e.g. 4.4), powers (e.g. 44), square roots, factorials (4!), and overbars for repeating digits (e.g. .4 with an overbar to express 4/9). Ordinary use of parentheses are allowed. One of the trickiest numbers to represent in this way is 73, which calls for something as a contorted as √(√(√(44!))) + 4 / .4' (where .4' is shorthand for .444...). Of course, the problem can be extended to represent integers greater than 100. The highest value achievable in the four four's puzzle is 10 ^{8.0723047260281×10^153} =
4^{4^4^4}. S. K. Johnson has pointed out that a higher value, using the factorial, is 4! ^{4!^4!^4!}. Thanks to Amory Wong for pointing out that an
even larger value is 4444! ## Related categories• GAMES AND PUZZLES• ARITHMETIC | |||||

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