# Get 100 as an answer on a calculator without using 0

Task

Get 100 as an answer with only four keystrokes on a regular calculator.

Disallowed keys

• 0
• 00

Allowed keys

All other than the aforementioned two keys.

Take the below image as a reference. Condition

Atleast two operators must be used.

• This question can be found a few different times online: in.answers.yahoo.com/question/index?qid=20111021032155AA4ke5E & quora.com/… you have just added the two operator condition – n_plum May 9 '17 at 17:40
• Does pressing = count? – theonlygusti May 9 '17 at 19:15
• @theonlygusti Yes – Nikhil Bhavar May 9 '17 at 19:17
• Might I suggest "only four keystrokes" instead of "only four buttons" in the wording of this. I could easily complete this task using 1=1+ and simply hammer the "=" sign until 100 is shown on the display. Don't make it easy for the devious :) – Wossname May 9 '17 at 19:20
• Scientific calculator allowed or basic calculator only? Also, must every press have a purpose? – OldBunny2800 May 9 '17 at 22:20

## 6 Answers

On my actual junky little calculator, these four button presses give 100:

$1$
$\div$
$\%$
$=$

In fact, any non-zero digit will work. Calculators will just use the current value in the display as the operand if you didn't type a new one, so what you're doing is saying: Start with $1$. Divide it by ... (the still displayed) $1$ turned into $1\%$, or $0.01$. Then hitting $=$ gives the answer of $100$.

Also, try it here:
https://www.theonlinecalculator.com/
which behaves the same way.

• @CalvT 5% is .05. 5 / .05 is still 100. – Rubio May 9 '17 at 17:59
• @Rubio I get 20, as I get 5% of 5, which is 0.25, so 5 / 0.25 – CalvT May 9 '17 at 18:00
• @Siguza Looks like you hit "$+$" (PLUS) instead of "$\div$" (DIVIDE)? – Rubio May 9 '17 at 18:12
• the percent key means "take x% of the preceding result", so 5 / (5%) is 5 / (5% of 5) = 5 / 0.25 = 20 – ffao May 9 '17 at 18:13
• @ffao Actually the $\%$ key on a calculator just means "divide by 100", and it does exactly that. (Following addition/subtraction it gets a little weirder, but following multiplication/division that's all it is.) Try it on the calculator site I posted. $5 \div \% =$ will give $100$. – Rubio May 9 '17 at 18:17

It is

1/1%

because

1/1 = 1 and 1 expressed as a percentage would be 100%. Note that I didn't have to press the = sign in my calculator to get to the 100.

• You need to hit = to make this give the result, which would be a fifth keypress – Sconibulus May 9 '17 at 17:30
• Unless they mean 'press 4 buttons' meaning any number of presses but you can only use 4 different keys (1, /, %, =) – n_plum May 9 '17 at 17:36
• 1 in percentage is 0.01 – Nikhil Bhavar May 9 '17 at 17:48
• @Sconibulus Didn't think about it coz my calc calculated it without pressing the = sign :/ – manshu May 9 '17 at 18:53
• = is a fifth button press. Similarly, there's 4x25 (which is the one that I came up with, until I saw the OP's comment that mentioned that = counts as a button press. +1 anyway. – Shokhet May 10 '17 at 0:04

I found another solution.

.1 first and second key, 1/x third key, x2 fourth key. You need a calculator with those buttons though.

The OP says that calculator is just for reference, meaning I can use "a regular calculator" that's slightly different? It's the standard calculator that came with my windows 10.

On the Windows 7 default calculator the following works

1 % = But then again you have to add the / to make it two operators I guess

• Then this is the same as @Rubio's answer, no? – boboquack May 9 '17 at 23:31
• Don't you mean 1/%= and not 1%=? – Rand al'Thor May 10 '17 at 0:06
• Interesting, this only works if you had been playing with the other method beforehand. Therefore when you hit 1/%= then proceed to hit 1%= it works but not otherwise, can anyone explain what carries over from the first equation to make the second one work? I always assumed it started with a new calculation after you hit equals unless you continue with a new operator. – J. Knight May 10 '17 at 21:18

You can do it with 3 mouse clicks on a virtual claculator (Windows or Mac):

With the calculator in "programmer" mode, base 16 selected, click 6 4 "base 10"

And for the pedants that require 2 "operators":

With the calculator in "programmer" mode, base 16 selected, click 6 4 "base 10" =

• This doesn't use the keys shown on the reference calculator. – boboquack May 10 '17 at 0:04
• -1. Not a "regular calculator", and you did not use two operators, both of which are indicated in the puzzle. – Rubio May 10 '17 at 0:04
• @Rubio I know. But lots of answers on this site "band the rules". I still like my answer. – Bohemian May 10 '17 at 0:07
• Then I could "bend the rules" by choosing to ignore the rules I don't like also. My solution is thus: $1 \ \ 0 \ \ 0$, et voila. (Yeah, you can't just toss away the rules, or anarchy wins!) – Rubio May 10 '17 at 0:09
• There is no lateral thinking tag which means, don't bend the rules to the question. – n_plum May 10 '17 at 0:11

You can press 25 x 4 to get 100.

• That wouldn't work; you'd need to press the = key as well. (The calculator might think you want to type 25x41=) – Glorfindel May 9 '17 at 19:57
• (Also doesn't use two operators, as required.) – Rubio May 9 '17 at 20:30
• "That wouldn't work; you'd need to press the = key as well." It will work with an RPN calcluator: 25<enter>4* – radarbob May 10 '17 at 2:56
• You used five keystrokes total. – oemb1905 May 10 '17 at 3:00
• @radarbob Nope, 2, 5, Enter, 4, * is 5 keystrokes. – jamesdlin May 11 '17 at 0:46