The scale of nanometer

People can recognize things as large as a millimeter. One-thousandth of a millimeter is 1 micrometer, which is the size of protein and cells. One-thousandth of a micrometer is one nanometer, which is a millionth of a millimeter.  In order to make it possible for people to recognize things as large as a nanometer, it is necessary to magnify them hundreds of thousands of times to a million times.