2 num - numerator of a real number
13 For real x, den(x) returns the denominator of x. In calc,
14 real values are actually rational values. Each calc real
15 value can be uniquely expressed as:
25 If x = n/x, then den(x) == n.
28 > print num(7), num(-1.25), num(121/33)
35 NUMBER *qnum(NUMBER *x)