![Wink](https://bitcointalk.org/Smileys/default/wink.gif)
Nah, you cant use the calculation from the streamer as the streamer use the calculation based on the base bet. The same as used by the providers especially Pragmatic Play and No limit. If you are familiar with this 2 providers, all the bets history is based on the base bet even if we are playing buy bonus. Different calculation is applied for bet history on the casinos and for the challenge or any other multiplier contest in most casinos.
Lets take some example from my own bets on rollbit with buy feature below:
![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2FsnmfUyT.png&t=629&c=B7j6jW3Z-GSztA)
From the screenshot above you will know how the multiplier works, it is = payout/wager. If bonus buy multiplier works based on the base bet then my multiplier will be different unlike what you can see on my screenshot.