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Am sorry for causing confusion please if you live outside us then refer to this page after logging in https://www.binance.com/en/earn you will see the exact APR% for flexible and fixed staking for each and every coin hope this helps you out.

Hm no that's actually even more confusing :D
No worries though this is a question that many have asked with no answer.
Seems to be shrouded in mystery.

I think it is seen as a mystery cause the APR% some how changes every day perhaps this might be the reason.

I guess they get that from loans

and other sophisticated financial products