[NamTaf]

I feel you can do something with floor and trunc to get the remainder, then using round to get the sig figs correct. You can make it abs of it at the start, and then only add a negative at the start of the concat if it's negative.

I rapidly tried and I get something a bit shorter (about half the length), but my rounding ends up with imperfect precision and sometimes I get 10m60s rather than 11m0s due to it. Appropriate rounding at the appropriate points would fix that.