
theorem Th149:
Sum digits(112,10) = 4
proof
  thus Sum digits(112,10) = Sum <%2,1%>+Sum <%1%> by Th148,AFINSQ_2:55
  .= (2 + 1) + Sum <%1%> by AFINSQ_2:54
  .= 3 + 1 by AFINSQ_2:53
  .= 4;
end;
