# What number + 1 equals itself? [closed]

The answer is not an integer. The answer is in string form. The answer is not my love life...

• Is this really a puzzle? – Rubio Mar 18 '19 at 15:51
• It is confusing that "the answer is in string form" however you ask for an answer "in numerical form". Given this wording it appears that you are expecting the answer to be related to programming. In programming there is usually +ve infinity, -ve infinity and NaN. I'm guessing that "The answer is not my love life" is a joke to rule out NaN. My point is that if infinity is the answer that you are expecting then you've kinda mixed up programming and mathematics since infinity and NaN are values in programming however they aren't actually numbers. Even then @Rubio 's point still holds – Adam Mar 18 '19 at 18:13
• @Adam NaN doesn't actually work, though, as it doesn't equal itself. +1 or not. – John Dvorak Mar 18 '19 at 19:36
• @JohnDvorak however as a string it does! It really depends on the interpretation. Even then we don't know whether the question was asked with the lack of this knowledge or not – Adam Mar 18 '19 at 20:15

Is it

Infinity ∞, because infinity + 1 = infinity

• I hope not, because infinity is not a number. – GentlePurpleRain Mar 18 '19 at 15:58
• @GentlePurpleRain Yeah you're right, but it also says the answer is not an integer.. I don't know – pirate Mar 18 '19 at 16:06
• @GentlePurpleRain isNaN(1/0) == true – John Dvorak Mar 18 '19 at 16:07
• [(1/0.0).is_a?(Numeric), (1/0.0).is_a?(Integer)] == [true, false] – John Dvorak Mar 18 '19 at 16:09
• It is a number in some number systems. – noedne Mar 18 '19 at 16:28

Some have expressed concerns whether infinity is a number. My proposal definitely is.

In JavaScript notation:
x = new Number(); x.value = 0; x.valueOf = function(){return this.value++}
x + 1 == x // true