The most common rate i've seen is 15k per USD, so if you buy 125 USD worth of tc for 15k per usd, you'd be buying 1,875,000 tc. If you aren't sure how much you are buying, just get a calculator (if you don't have a calculator at home you can use an online calculator) and do Rate x Amount, i.e. 15,000 times 125 = 1,875,000