# probability

`import { probability } from "destack:simulation/scenario";`

Create a trigger that fires with probability in parts per million.

```ds title="probability"
export function probability(probabilityPpm: uint32, on?: EventKind | undefined): Trigger
```

[language/library/src/simulation/scenario/trigger.ds:88:90](https://github.com/destack-sh/destack/blob/main/language/library/src/simulation/scenario/trigger.ds#L88-L90)