
theorem Th905:
Sum digits(2244,10) = 12
proof
  thus Sum digits(2244,10) = Sum <%4,4,2%>+Sum <%2%> by Th904,AFINSQ_2:55
  .= Sum <%4,4%> + Sum <%2%> + Sum <%2%> by AFINSQ_2:55
  .= (4 + 4) + Sum <%2%> + Sum <%2%> by AFINSQ_2:54
  .= (4 + 4 + 2) + Sum <%2%> by AFINSQ_2:53
  .= 10 + 2 by AFINSQ_2:53
  .= 12;
end;
