A broken calculator has only the keys:
+(addition), -(subtraction), /(division), x(multiplication), =(equals)
It is a simple calculator that can do one binary operation at a time.
The only functional digit is 7.

How is it possible for 34 to appear in the readout in the fewest number of keystrokes?

Notes:

1. Performing as many operations as possible is allowed.

2. The digit 7 may be reused, that is expressions like 777x77 or, 7777+7 in a given operation is allowed.

(In reply to possible way - spoiler by Ady TZIDON)

"It is a simple calculator that can do one binary operation at a time."

Given the above statement, the broken calculator would require the equal key pressed for each binary operation. Assuming that the initial default value in memory is zero and is not counted as one of the two operands in the operation -7/7, the number of keystrokes required for your proffered expression, with the appropriate equals keystrokes, would be 20: -7/7 = +7 = +7 = +7 = +7 = +7 =.

Posted by Dej Mar on 2013-07-31 12:33:42