What is the main advantage of using a system of multiple pulleys?

A system of MULTIPLE PULLEYS reduces the FORCE needed to lift a load by providing MECHANICAL ADVANTAGE. ASVAB Mechanical Comprehension tests pulleys. A single fixed pulley just changes the direction of force (no force reduction). Adding movable pulleys (a block and tackle) reduces the force needed — but you must pull the rope a greater distance (trade-off: less force over more distance). The mechanical advantage roughly equals the number of rope segments supporting the load. Understanding that pulleys reduce required force is commonly tested.