Of all simple machines, the mechanical advantage is easiest to calculate for pulleys. To find out the mechanical advantage of a Pulley, simply count the number of ropes supporting the load. That is the IMA or Ideal Mechanical Advantage of Pulley.
Once again we have to exert force over a longer distance to multiply force. To raise a load 1 meter with a pulley system you have to pull N meters of rope.
Pulley systems are often used to raise flags and window blinds and are part of the mechanism of construction cranes.
Read about Pulley Numerical Problems