Complex sentence: A calculating machine is a machine designed to come up with calculations (i.e. computations); the most famous is probably the Victorian British scientist Charles Babbage's Difference Engine (No.2), designed in the 1840s but never completed in the inventor's lifetime.
Split into simpler sentences: A calculating machine is a machine designed to come up with calculations or, in other words, computations. The most famous is probably the Victorian British scientist Charles Babbage's Difference Engine (No.2), designed in the 1840s but never completed in the inventor's lifetime.