Add, subtract, multiply or divide two fractions — result is automatically simplified.
After the arithmetic, the result's numerator and denominator are both divided by their greatest common divisor (GCD), so you always get the fraction in lowest terms.
Dividing by a/b is the same as multiplying by its reciprocal b/a, so a/b ÷ c/d is computed as a/b × d/c — that's why the calculator cross-multiplies (ad) over (bc).
It only appears when the result is an improper fraction (numerator ≥ denominator). It shows the same value split into a whole number plus a proper fraction remainder, e.g. 7/2 becomes 3 1/2.