Express 31 by 4 successive digits, using no more than 4 out of 5 basic operations (i.e. + - / * and exponentation), nothing else allowed.
No brackets!

The order of the digits must be an arithmetic progression like 8*7-6-5 or 3+4*5+6, examples fitting the specifications but not the result.

31 = 7 * 5 - 3 - 1
31 = 9 + 7 + 5 * 3


Permitting concatenation of the basic operational symbol for subtraction, i.e., using it as signage for negative numbers:
31= -5 + 4 * 3^2
31 = -1 + 2^3 * 4

Edited on August 16, 2018, 3:13 pm

Posted by Dej Mar on 2018-08-16 15:05:49