My mathematic is not very good
When play online, that is ok because I can change the chips to BB
But in live tournament, for example BB is 1400, and I have 23000 chips
I don't know how many big blind I have
I try search on YouTube, but I didn't found
Is there any good source for learn mental arithmetic? Thanks!

Here is a quick tip -- drop off an equal number of zeros from the big blind and your stack. So in the example above 1400 BB and 23000 chips becomes, 14 BB and 230 chips after dropping off 2 zeros from both. The math is now considerably easier: 230/14. We can do some more approximation by knowing that ten BBs would be 140 (10x14), so if we take away those ten BBs we have 90 units left. So we have 10 BBs + 90/14. Quick approximation in our head tells us 90/14 is around 6 (6x14=84) or 7 (7x14=98). So we can approximate pretty quickly, easily and accurately that we have between 16 and 17 BBs.

The actual math is 23000/1400= 16.429, which you could probably do on the calculator function on your phone when you are not a hand.

Good answer. I don't have a quick and easy rubric myself, but I do find trying to figure out my stack in chunks of 5 or 10BB and then calculating what's left can make it easier.

Thank you so much for your tips. I had problem especially on the late stage of live tournament when millions of chips involve

The tournament clock also contains a ton of valuable info about chips in play, average stack, upcoming blinds to use compared to your chips

Just multiply the BB by 10.

In this case it is 14,000. You have 23,000 chips so it is less than double 14,000 which is 28,000. So you have between 10 bb's and 20 bb's. 23,000 is 9,000 more than 14,000 which is more than half of 14,000. So you have more than 15 blinds. At that point to me it doesn't matter exactly how many bb's I have because it is over 15 and less than 20. So I am 3-betting all in and my opening pre-flop raise will be a min raise.

If you have say 43,000 chips. then you would do the 10bb thing to 14,000. Then 20 bb to 28,000. Then 30 bb to 42,000. So you are just over 30 bb's. And so on.

So for me it is about what betting strategies I have at my range of bb's. I particularly care if I have < 15 bb's, between 15bb's and 25bb's, between 25 bb's and 40 bb's, less than 80 bb's and then less than 120bb's.

Multiply 1400 by 10x, 20x, etc until you go over your stack. So you know you have more than 10bb, that would be 14,000, and you know you have less than 28,000, that would be 20bb. You know it's closer to 20 than it is to 10, so it is more than 15. So even if you are like, okay I have 16-19bb, in a pinch, that is a decent approximation.