Numbers iPhone: Formula results lose Duration format

Two thinks stand out in your post...

You do need to be careful with duration, since how Numbers interprets your value may not be the same as you expect when you enter values directly.

Numbers also uses the format as a hint to the units you're entering.

If you're using 'Automatic Units' then numeric value will be interpreted as days (and displayed as number of weeks/days if >7), so I'd expect your 119.25 value to display as '17w 0d 6h'

To override this you can provide units of measure in the input - for example, 119 hours and 15 minutes could be entered as either:

119.25h -> the 'h' tells Numbers you've specified a number of hours

119h15m -> the 'h' and 'm' tell Numbers that you've specified Hours and Minutes

If you're not using Automatic Units, then Numbers will use the largest unit selected as a hint. For example, if the format is set to:

then '119.25' will be interpreted as 119 minutes and 15 seconds, since 'min' is the largest unit selected in the format.

So it sounds like you need to play with the format a little to give Numbers a hint as to how you want to enter your data. It's quite flexible at the end of the day, but it does have a few gotchas.

> But if I create a formula of cubic feet / cubic feet per minute &’m’ all I get is 119.25m

Ahh... and here's the kicker - you're not getting a Duration value at all. You're getting a text value... sure, one that you might look at and see a duration, but to numbers, something like:

=(B2÷C2)&"m" 

is a text result. That's why the format is changing on you.

In order to get this as a Duration value, you need to be more explicit, via the DURATION() function:

=DURATION(0,0,0,B2÷C2)

Duration takes a number of weeks, days, hours, minutes, seconds and/or milliseconds and returns an actual Duration value that can be used with other numeric functions.