M Language (Excel 2016 Get and Transfom) Add several columns with totals

[Ozz33]

The data source has columns 1 to 25. I need to insert several Totals columns each adding the values of 5 columns (Total1 = Col1+Col6+Col11+Col16+Col21; Total2 = Col2+Col7+Col12+Col17+Col22; .........;Total5 = Col5+Col10+Col15+Col20+Col25)
Other than manually adding five lines of Table.AddColumn, one for each total, is there a way to use a single line command? the real case consists of 375 columns, not 25.
Thanks in advance;