Explain, using an example, why need to multiply when converting from a larger unit to a smaller unit?

Because you need more of a smaller unit to equal a larger unit.

Example:

If you want to convert 5km to meters, there must be more meters than kilometers.

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.

4444444444444 i think