PRIME NUMBER: A whole number that can only be divided evenly (that is, without a remainder) by itself and 1.
COMPOSITE NUMBER: A whole number that can be divided evenly by some other integer other itself and 1.
PRIME FACTOR (of a composite number):
A prime number that can be divided evenly into the composite number.
The following exercise checks your ability to factor composite numbers into their prime factors. (Works best on an HTML standard 4.0 or later.)