# Big O: Constants don’t matter

23 April 2023 (Updated 23 April 2023)

### In a nutshell

Consider this function:

```
function countUpAndDown(n: number) {
console.log("Going up!");
for (let i = 0; i < n; i++) {
console.log(i);
}
console.log("At the top!\nGoing down...");
for (let j = n - 1; j >= 0; j--) {
console.log(j);
}
console.log("Back down. Bye!");
}
countUpAndDown(10)
```

Even though technically the Big O here is `O(2n)`

(we loop `n`

times twice), we simplify the Big O to just `O(n)`

. We drop the constant before `n`

.

Here are some examples of dropping constants:

`O(2n)`

->`O(n)`

`O(100)`

->`O(1)`

`O(14n²) -> O(n²)`

Tagged:
Big O Notation

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