Shorten formula - summing dates

[psrs0810]

How can I shorten the formula:
=SUM(DAY(EOMONTH(A156,0)),DAY(EOMONTH(A157,0)),DAY(EOMONTH(A158,0)),DAY(EOMONTH(A159,0)),DAY(EOMONTH(A160,0)),DAY(EOMONTH(A161,0)))

I tried doing sumproduct, but I must be doing something wrong
Thanks

 

[Rick Rothstein]

This will produce the same answer as the formula you posted...

=SUMPRODUCT(DAY(DATE(YEAR(A156:A161),MONTH(A156:A161)+1,0)))

 

[Tetra201]

Here is a shortened formula:

=SUMPRODUCT(DAY(EOMONTH(+A156:A161,0)))