1 sat is 0.00000001 Bitcoin
Each day, you can win 250 sats on Okex exchange.
Go in More Tab, and select Free Bitcoin
You'll have Daily Mission (5/5) : Just click on one, and wait 60s. You can claim 50 sats, 5 times, means 250 Sats. Easy, no ?
Don't have an Okex account yet ?
https://www.okex.com/join/1/2440265 : You will have 10$ if you buy 100$ or more Crypto