An arithmetic (pronounced er-ith-MET-ik) progression is a sequence of numbers in which the difference between succeeding terms is the same number: 1, 4, 7, 10, 13, etc. A geometric progression is a sequence of numbers in which the ratio of each number to the one it follows is the same: 1, 2, 4, 8, 16, 32, 64, etc. A mathematical progression is a sequence of numbers in which each succeeding number is obtained by the action of the same rule on the preceding number; hence both arithmetic and geometric progressions are mathematical progressions.
