When using power tools, never engage the trigger lock. Before replacing parts such as bits, blades, or discs on any tool, you must disconnect the power source. Most hammer drills will not hammer until pressure is applied to the drill bit. A pneumatic drill is commonly used when there is no source of electricity.
This is because you need to set up the equation _ % of _ is _ and then plug in numbers. _% of 377 is 217 is the final equation. Then divide 217 by 377 which is 0.57559681697. Then you round to the nearest hundredth to get 58%
