Taking a page from your approach, here is an array-entered formula** that can be placed directly in A2 and copied down as well...

=A1+11-(MOD(SUM(--(MOD(A$1:A1,10)=0)),2)=1)

**Commit this formula using Ctrl+Shift+Enter, not just Enter by itself.

--
Rick (MVP - Excel)


"Glenn" wrote in message ...
Glenn wrote:
Mark Watlock wrote:
I was asked by a co-worker to create a formula to do this but have
drawn a blank. Any ideas?
The next number increases by 11 until last digit is 0 then increases
by 10 then 11 again
2619 2630
2640
2651
2662
2673
2684
2695
2706


A single formula solution. With your starting number in A1, put this in
A2 and copy down:

=A1+11-(MOD(COUNT($A$1:A1)+RIGHT($A$1,1),11)+1=1)


Not sure how I ended up with "+1=1" at the end of that, but obviously this would
work as well:

=A1+11-(MOD(COUNT($A$1:A1)+RIGHT($A$1,1),11)=0)