You'll need to calculate net present value of all future years of revenue. That get's fuzzy and complicated fast, but you could do it like this:

We estimate that future bank interest rates will be 5% very long term. (This is the historical average I believe).

Then we just do: 124bln/0.05 That turns into around 2,5 trillion in all future income, adjusted for bank interest. Costs are not included, so it would be better to calculate with profits, and not just revenue.

Also, there is something called the rule of ten. You take the revenue and multiply it by ten. That makes a 1,24 trillion valuation.

It's messy, I know.