Friedman
A Friedman number is a number that can be
represented with an expression that uses only the digits in the number. In
addition, the expression can include +, –, ×, ÷, exponents and parentheses, but
nothing else. For instance, 25 is a Friedman number because it can be
represented as 52. A nice
Friedman number is a Friedman number for which the digits occur in the same
order in the expression as they do in the original number.
So, 343 is a nice Friedman number, because it can be represented by an
expression with the digits 3, 4, and 3 in the same order:
343 = (3 + 4)3
The first
seven nice Friedman numbers are 127, 343, 736, 1285, 2187, 2502, 2592. Can you
find an expression for each of them?
This brainteaser was
written by Derrick Niederman.
