# WDI-PANTHALASSA
---
Title: Arithmetic or Geometric
Type: Morning Exercise
Duration: 45 mins
Creator: Thom Page
Course: WDIr-Panthalassa
---
## Arithmetic or Geometric sequence?
Write a method `arith_geo` that takes an **array of numbers** and returns the string "Arithmetic" if the sequence in the array follows an arithmetic pattern, or returns "Geometric" if it follows a geometric pattern. If the sequence doesn't follow either pattern return -1.
An **arithmetic sequence** is one where the difference between each of the numbers is consistent, eg. the difference between each number is `5`.
Whereas in a **geometric sequence**, each term after the first is multiplied by some constant or common ratio.
```
Arithmetic example: [2, 4, 6, 8]
```
```
Arithmetic example: [20, 28, 36, 44]
```
```
Geometric example: [2, 6, 18, 54]
```
```
Geometric example: [6, 12, 24, 48]
```