How the torque increases when we reduce the gear?

Question

How the torque increases when we reduce the gear?

Answer 1

The only thing to add is the previous answer is that energy or power must be conserved.  Power is proportional to torque times rotational speed.  Therefore, if the torque is doubled in a gearbox, then the output speed will be reduced by a factor of two.

Answer 2

Mechanical advantage works the same as through a lever.

Force / distance.