integer division

[Werner]

As part of a long division, I need to do the following on the 42S (but it applies to all HP calculators that do not have a DIV command):
Given C and X, C<X
determine Q and R so that

C*10^12 = Q*X+R

C,Q,R,X positive and less than 10^12

Sounds easy? It isn't, or I am missing something.
R is easy: MOD(C*10^12,X), absolutely correct.
Now for Q..

Try:

C=2 and X=3 (Q=666 666 666 666, R=2)
C=2e11+3, X=4e11 (Q=500 000 000 007, R=2e11)

Can you get the correct Q? For the second example, I still can't ;-)
(Well, that is not strictly correct: of course I can, but not quickly and elegantly :-)

Werner