# Number and Letter Series

### Types of Number Series

- Prime Number Series
- Difference Series
- Multiplication Series
- Division Series
- Square Series
- Cubic Series

### Letter Series

In these types of problems, a series of the letters of alphabet is given which follow a specific pattern or a sequence. The letter series mainly consists of skipping of the letters. To solve such problems, assign numbers 1 to 26 to the letters of the alphabet. In some cases it may be useful to assign the numbers in the reverse order.

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 |

A | B | C | D | E | F | G | H | I | J | K | L | M |

Z | Y | X | W | V | U | T | S | R | Q | P | O | N |

26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 |

Above table shows both forward as well as reverse place value of any alphabet.

Sum of forward position and reverse position for any alphabet is always constant and equal to 27. For example, sum of both positions of G is (7 + 20 = 27).