The first step of the construction of Nezondet's models of finite arithmeti
cs which are counter-models to Erdos-Woods conjecture is to add to the natu
ral numbers the non-standard numbers generated by one of them, using additi
on, multiplication and divisions by a natural factor allowed in an ultrapow
er construction. After a review of some properties of such a structure, we
show that the choice of the ultrafilter can be managed, using just the Chin
ese remainder's theorem, so that a model as desired is obtained as early as
at the first time.