Is there a way to test in a formula if a text field contains a valid number?

There may be other ways but this might be quick and dirty as a formula checkbox field.  But this will fail if the number has a leading zero like 0123.  If that is possible, then the formula will need to be a bit fancier.


ToText(ToNumber([maybe a number]))=[maybe a number]

Thanks Mark. That's clever, but I couldn't get it to work. For my current purposes, this seems to have done the trick. 

Length([Subject Form ID]) > 0 and Left([Subject Form ID],1) >= "1" and Left([Subject Form ID],1) <= "9"

It really bugs me, though, that there isn't a native function to do something so straightforward and necessary.

I did test that formula and it did seem to work for me ... did you have a string that failed that I could test it on.  The useful idea is that the ToNumber( ) function will return blank it what you give it contains non numeric characters.

In my test, the field for [maybe a number] was a text string.

Yeah, I would have though it would work for me,but it didn't. The particular piece of text that was a problem was 'Oneil  (starting with an apostrophe). For my purposes, I am extracting FormID's which are all positive integers from 2 to 5 digits long, so I took the simple way to just test the first character, but I would like to get your more universal approach to work too, for what I'm sure will be later needs for this functionality.

I tried 'Oneil on my formula and it correctly said it was not a number

Hmm. Thanks for letting me know. I'll have to go back and do some more testing when I have time. Too much else going on with this project right now - I need to keep moving. Thanks again for your help!

I would avoid getting into a situation where you have either text or a numeric value in a text field in the first place. Rethink your fields and calculations. Ambiguous data (text/numbers) should be cleaned up at the point of key entry or importing.

You probably could do a simple formula knowing that a number in a business setting consists of a {set of digits} possibly proceeded by a plus or minus sign and at most one decimal point  amid the digits but it is just an exercise if difficulty.

QuickBase does not use scientific notation for numbers but technically you could have this in your string and ToNumber () will convert it correctly.

ToNumber("34e5") => 3400000

Or you could use JavaScript where any manner of parsing and data conversion is possible. Anyone here that could write a formula to accomplish the task you ask about could do it easier in JavaScript. Replace the formula language with JavaScript is my advice.

It strikes me as extremely odd that for a no code platform the first thing you have to do is master the formula language and all its quirks.   _\_(_)_/__

Sorry to resurrect an old post but this is the closest post I've found that's similar to the problem I'm struggling with. 
I have a text field that's supposed to have all numbers except for dashes. I need to do IsNumeric type of validation. While Mark's formula is working great, my field can start with 0 so I can't use it. And changing the field to numeric is not an option at this point due to other dependencies. I've tried many different approaches with no luck. Any help would be greatly appreciated.