Change your code to:
\documentclass[a4paper,11pt]{report}
\usepackage[turkish]{babel}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage{calculator} % 2014/02/20 v.2.0
\usepackage{calculus} % 2014/02/20 v.2.0
\begin{document}
Ş ş Ç ç % Before
\newcommand\gga{10}
\newcommand\ggb{30}
\newcommand\ggc{5}
\newcommand\ggd{5}
\newcommand\gge{10}
\newcommand\ggf{9}
\ADD{\gga}{\ggb}\sola
\ADD{\ggc}{\ggd}\solb
\ADD{\gge}{\ggf}\solc %<----- This Line
\show\c \show\solc % Look into the log file
Ş ş Ç ç % After
\end{document}
It seems that your used macro \c
has another definition and gives the problem. Follow the documentation and use varaiables \solx
for your solutions. Change x
to what you need, for example c
.
With \show
you can see in the log file, what the following macro means. The result for my MWE is:
> \c=macro:
->\T1-cmd \c \T1\c .
l.25 \show\c
\show\solc
> \solc=macro:
->19.
You see, macro \solc
has the value 19.
Result in your pdf:

At last the reason for this behaviour is that \usepackage[utf8]{inputenc}
translates Ş into \c{S}
(and similarly for the other letters with the cedilla). \c
marks the "cedillia" that is added to the following letter (here in the example S
). Now you redefined the cedillia to 19
so you get at last \c{S}
--> 19{S}
--> 19S
. And so redefining \c is definitely a bad idea, especially for Turks (Thanks to @egreg for his great comment!)
\b
,\c
,\d
,\H
,\k
,\r
,\t
,\u
,\v
). – jon Oct 11 '15 at 6:17\c
(to\gamma
, because he knew Greek), but that particular paper had a Turkish coauthor whose surname started withŞ
. Don't use\def
unless you have a good reason to; packages such ascalculator
that do redefinitions without any check are to be avoided, in my opinion. Use some distinguishable prefix, like you did at the beginning. – egreg Oct 11 '15 at 9:39