45 minutes sprint

# Algorithm
Question

Given the triangle of consecutive odd numbers:
```
             1
          3     5
       7     9    11
   13    15    17    19
21    23    25    27    29
```

Calculate the row sums of this triangle from the row index (starting at index 1).

**Solution should by written in PHP**

E.g.
```
rowSumOddNumbers(1); // 1
rowSumOddNumbers(2); // 3 + 5 = 8
```


# Database
Given a table with the following.

| id | name    | email            | role_id  |
|----|---------|------------------|----------|
| 1  | Jon     | jon@example.com  | 1        |
| 2  | Peter   | pete@example.com | 1        |
| 3  | Stanley | stan@example.com | 1        |
| 1  | Jon     | jon@example.com  | 3        |
| 1  | peter   | jon@example.com  | 3        |

Write an SQL query that selects distinct emails where role_id is equal to 3 or 1.

Example Result.

| email            |
|------------------|
| jon@example.com  |
| pete@example.com | 
| stan@example.com | 

# Frontend
Todo list app
NB: Focus on functionality not, how good it looks.
- Add Todo
- Remove Todo
- Toggle completed status
- Change todo text