Add up the numbers in the following array.
`[1, 2, 3, 4, 5, 6]`
The sum of the numbers in the input array is 21.
Complete the following task based on the instruction and optional input provided.### Instruction:
Add up the numbers in the following array.

### Input:
`[1, 2, 3, 4, 5, 6]`

### Output:
The sum of the numbers in the input array is 21.