BPM finder, implemented in a button

1. How to convert to BPM?
2. 1 Minute = 60 seconds = 60,000 ms.
3. We can divide that by our interval to get BPM
4. Sadly we get a really long number with a misleading amount of precision.
5. Apart from manually clamping, is there a way to protect the significant digits?
6. Answer: javascript numbers have a built in "toPrecision()" that does what we need,
7. apart from returning a string for some weird reason.