
theorem Th885:
Sum digits(2002,10) = 4
proof
  thus Sum digits(2002,10) = Sum <%2,0,0%>+Sum <%2%> by Th884,AFINSQ_2:55
  .= Sum <%2,0%> + Sum <%0%> + Sum <%2%> by AFINSQ_2:55
  .= (2 + 0) + Sum <%0%> + Sum <%2%> by AFINSQ_2:54
  .= (2 + 0 + 0) + Sum <%2%> by AFINSQ_2:53
  .= 2 + 2 by AFINSQ_2:53
  .= 4;
end;
