Numerator of a fraction after simplification

The numer or getNum command finds the numerator of a fraction.

numer takes r, a fraction.
numer(r) returns the numerator of r after it has been reduced to lowest terms. (For rational expressions, see Section 11.6.2 and Section 11.6.1.)

numer(42/12)

or:

getNum(42/12)

To avoid simplification, the argument must be quoted (see Section 9.1.4).

(For rational fractions see Section 11.6.1).

numer('42/12')

or:

getNum('42/12')