I tried to compile following sample, using initialization with a long unsigned int parameter of class big<>:

#include <ttmath/ttmath.h>
#include <iostream>

int main()
{
typedef ttmath::Big<1,2> MyBig;
long unsigned int c= 124743892;
MyBig b(c);
}

gives:
$ g++-4.4 -c -Wall -pedantic -s -O2 -I.. -DTTMATH_DONT_USE_WCHAR big3.cpp
big3.cpp: In function ‘int main()’:
big3.cpp:8: error: call of overloaded ‘Big(long unsigned int&)’ is ambiguous
../ttmath/ttmathbig.h:3658: note: candidates are: ttmath::Big<exp, man>::Big(const ttmath::Big<exp, man>&) [with unsigned int exp = 1u, unsigned int man = 2u]
../ttmath/ttmathbig.h:3311: note: ttmath::Big<exp, man>::Big(ttmath::slint) [with unsigned int exp = 1u, unsigned int man = 2u]
../ttmath/ttmathbig.h:3291: note: ttmath::Big<exp, man>::Big(ttmath::ulint) [with unsigned int exp = 1u, unsigned int man = 2u]
../ttmath/ttmathbig.h:3148: note: ttmath::Big<exp, man>::Big(float) [with unsigned int exp = 1u, unsigned int man = 2u]
../ttmath/ttmathbig.h:3139: note: ttmath::Big<exp, man>::Big(double) [with unsigned int exp = 1u, unsigned int man = 2u]
../ttmath/ttmathbig.h:3130: note: ttmath::Big<exp, man>::Big(ttmath::uint) [with unsigned int exp = 1u, unsigned int man = 2u]
../ttmath/ttmathbig.h:3122: note: ttmath::Big<exp, man>::Big(ttmath::sint) [with unsigned int exp = 1u, unsigned int man = 2u]