“There are 30 keys”
You could make the case that there are 12 keys, or some multiple of 12 keys, or near-infinite keys. But 30? Pretty random!
You could make the case that there are 12 keys, or some multiple of 12 keys, or near-infinite keys. But 30? Pretty random!
I could be wrong - I just guessed that from another data source (some PDF song sheets that have the key listed on the top right).