Arithmetic progression

Arithmetic progression is a term in mathematics for an arithmetic series, ie a sequence of numbers in which each of the number differs from the preceding number by a constant quantity.

For example:
2, 4, 6, 8, 10 is a set of numbers. We see that each of the number differs from the preceding one by a constant quantity 2. Therefore, these numbers are in arithmetic progression.

Another example:
10, 8, 6, 4, 2 is a set of numbers. We see that each of the number differs from the preceding one by a constant '-2'. Therefore, these numbers are in arithmetic progression.