Math mode for all numbers or not [duplicate]

Is there any reason to use/not use math mode for all numbers?

For example:

"The first few decimals of $\pi$ are $1$, $4$, $1$, $5$, $9$"?

"If you count in base $36$ every english word is a number: $h$ is $17$ and $hi$ would be $630$"

"There are $10$ types of people in the world..."

vs

"The first few decimals of $\pi$ are 1, 4, 1, 5, 9"?

"If you count in base $36$ every english word is a number: h is 17 and hi would be 630"

"There are 10 types of people in the world..."

In the first example, pi must obviously be in math mode or it won't display properly as the Greek letter pi. But the integers following that is not obviously one way or the other I think. I'd like to use math mode for the sake of consistency. Why would pi be more special than 1?

It the second example, I think it is obviously superior to use math mode for all numbers. If you don't, there is not really a way (for the compiler in particular but also readers) to distinguish what is a number and what are regular letters/words.

The third example I actually think is the hardest. If we look at it as a number, I think math mode makes most sense. But if we look at it as a word (I have a hard time forming this thought in word, but it feels like the number 10 is different from the meaning of the word "ten"), it kind of makes sense to treat it as a word (ergo not math mode).

To me it seems more natural to always use math mode when dealing with numbers, but it also seems like a pedantic thing no one in the right mind would do.

• Ignore the bad linguistic practice of writing out small numbers in numerical digits, in the third example. Also: I'm using the same practice for base 36 numbers as for hexadecimal numbers, thus it's 36 not 26; padding with 0..9 as the first digits. – lindhe Apr 20 '16 at 8:10
• – Torbjørn T. Apr 20 '16 at 8:11