
theorem Th371:
Sum digits(360,10) = 9
proof
  thus Sum digits(360,10) = Sum <%0,6%>+Sum <%3%> by Th370,AFINSQ_2:55
  .= (0 + 6) + Sum <%3%> by AFINSQ_2:54
  .= 6 + 3 by AFINSQ_2:53
  .= 9;
end;
