Worked example
Multiply 1/2 × 2/3 × 3/4
1/2 × 2/3 × 3/4 = (1 × 2 × 3)/(2 × 3 × 4) = 6/24 = 1/4
Three fractions, one rule. Multiply every numerator (1 × 2 × 3 = 6) and every denominator (2 × 3 × 4 = 24), then simplify 6/24 to 1/4. You could also cancel first: the 2s cancel, the 3s cancel, and you are left with 1/4 without ever building 6/24.