# B The largest number, does it end in 0 or 9?

1. Oct 10, 2017

### Orson

Does the largest number end in 9 or 0?

Last edited by a moderator: Oct 10, 2017
2. Oct 10, 2017

### Staff: Mentor

Yes - (I don't know)

Last edited: Oct 10, 2017
3. Oct 10, 2017

### Drakkith

Staff Emeritus
I was under the impression that there is no largest number.

4. Oct 10, 2017

### Staff: Mentor

There is no largest number.

5. Oct 10, 2017

### phinds

6. Oct 11, 2017

### diogenesNY

Perhaps it depends on the context.

I remember when I was much younger, I was frequently in a situation where the largest number was 32767.

diogenesNY

7. Oct 11, 2017

### phinds

I remember it well.

8. Oct 11, 2017

### I like Serena

The largest number - if it is defined - ends in 0 (actually, it is 0).
Reference: http://planetmath.org/node/84824
And no, this is not a joke. It's just that ordering of numbers is not quite unique.
There is an algebraic ordering based on divisibility that says that $a\le b \text{ if } a\mid b$.
That is, if a number divides another one, it cannot be greater.
And that puts 0 at the top.

Last edited: Oct 11, 2017
9. Oct 11, 2017

### jbriggs444

That seems to be cheating. By equally valid logic, I could say that the last digit of the largest number is 3. Take the standard total ordering of the integers and adjust it so that 123 is larger than all others. Done.

10. Oct 13, 2017

### I like Serena

Ordering based on divisibility has meaning and is used in number theory. It's not unusual that in specific scientific areas edge cases are defined slightly differently. And zero is definitely an edge case in algebraic structures.

11. Oct 16, 2017

### WWGD

If it ends in 9 , multiply it by 10, if it ends in 0, add 9.... SORRY, please delete.

12. Oct 16, 2017

### WWGD

If it ends in 9 , multiply it by 10, if it ends in 0, add 9....

13. Oct 16, 2017

If it ends in 9, cut off a finger and start over.

14. Oct 16, 2017

### FactChecker

Rinse and repeat.

15. Oct 16, 2017

### phinds

Oh, come on guys. Everybody knows that the largest number ends in the digits 42. I mean, where do you think Douglas Adams GOT the idea?

16. Oct 16, 2017