
theorem Th1242:
Sum digits(3075,10) = 15
proof
  thus Sum digits(3075,10) = Sum <%5,7,0%>+Sum <%3%> by Th1241,AFINSQ_2:55
  .= Sum <%5,7%> + Sum <%0%> + Sum <%3%> by AFINSQ_2:55
  .= (5 + 7) + Sum <%0%> + Sum <%3%> by AFINSQ_2:54
  .= (5 + 7 + 0) + Sum <%3%> by AFINSQ_2:53
  .= 12 + 3 by AFINSQ_2:53
  .= 15;
end;
