A slight modification to the fine code Luis posted should work for you. I changed the global temp table to instead use a temp table inside the dynamic sql. This may or not work for you. If you need to get at this data for more than just this select you may want to go back to the global temp table.

DECLARE @SQL nvarchar(MAX) = 'create table #Temp(TableName sysname, DateMod datetime, MyRowCount bigint);'

SELECT @SQL = @SQL + 'insert #Temp SELECT ''' + TABLE_NAME + ''' as TableName,

DATEADD( dd, DATEDIFF( dd, 0, _When), 0),

COUNT(*)

FROM [' + TABLE_SCHEMA + '].[' + TABLE_NAME + ']

GROUP BY DATEADD( dd, DATEDIFF( dd, 0, _When), 0);'

FROM INFORMATION_SCHEMA.tables

where TABLE_NAME like ('table%') --I added this part to help limit the tables since my test database does not meet your criteria for table structure.

select @SQL = @SQL + 'select * from #Temp;'

exec (@SQL)