
theorem Th1186:
Sum digits(2150,10) = 8
proof
  thus Sum digits(2150,10) = Sum <%0,5,1%>+Sum <%2%> by Th1185,AFINSQ_2:55
  .= Sum <%0,5%> + Sum <%1%> + Sum <%2%> by AFINSQ_2:55
  .= (0 + 5) + Sum <%1%> + Sum <%2%> by AFINSQ_2:54
  .= (0 + 5 + 1) + Sum <%2%> by AFINSQ_2:53
  .= 6 + 2 by AFINSQ_2:53
  .= 8;
end;
