Since things seem to be very quiet I thought I pose a small challenge for the season.

Given a memory cleared HP-12c what is the minimum number of keystrokes required to have 12.25 on the display.

Clearly, this can be done in five keystrokes. Can anyone do it in four or fewer?

If x^{2} was available without a shift key then here are two ways to do it:

3 . 5 x^{2}

7 x^{2} 4 /

Unfortunately, x^{2} isn't even present on the 12c.

Can anyone do this for other calculators? Assume the display mode is appropriately set (i.e. don't count any keystrokes for this).

- Pauli

here's one:

[3][5][ENTER][%]

another:

[.][0][8][1/x]

*Edited: 17 Dec 2008, 11:30 p.m. *

Quote:

[3][5][ENTER][%]

This is what I had in mind.

Quote:

[.][0][8][1/x]

Not quite, this is 12.50 which isn't quite right :-)

- Pauli

Quote:

Not quite, this is 12.50 which isn't quite right :-)

What can I say, I work in government :-)

In that case you should have found the two key solution:

[1][2]

:-)

Still a good effort finding the % solution.

- Pauli

Quote:

Can anyone do this for other calculators? Assume the display mode is appropriately set (i.e. don't count any keystrokes for this).

If you've set FIX 2, then

1 5 0 SQRT

will show 12.25 , again in 4 strokes.

The 12c has a square root function in an unshifted position?

News to me :-)

So this should really be:

1 5 0 g SQRT

at five.

Nice attempt nonetheless.

- Pauli

Oops! I don't have a 12C and didn't realize that it doesn't have an instant access square root (and I even wondered whether it did a couple of days ago, when I first thought about my scheme - and tested it on a 33S).