I know that most forex brokers let you trade money in the form of lots or fractions of a lot (i.e, 0.01 lots). But in case I want to trade, just to say, $542, is there a way to do it?
I know my request can seem stupid, but I figured out a way of profiting from trading forex, and this system only works if I am allowed to trade arbitrary amounts of money.

Answer
Hi, can I say that for one trade, you are allowed to lose up to $542 per trade?

If yes, then you will need to know from your strategy, what is number of pips measured from your entry price (EP) to your stop loss (SL) price?

And if you are trading EURUSD for example, 1 pip = USD$10.

You can use this formula Lot Size = (542) / nos of pips from your EP to your SL * $10

And if the trade does go against you and hit your stop loss, with the calculated lot size, you will lose up to $542 only.

Best Regards
Ah Kiat

minimum Initial investment for forex in micro account?

I want to start using forex (i have trained a lot on simulators), but now i would like to have a go at the real market. I know you can open micro accounts for as little as $50, but what do you think is the minimum amount of money you should put into your first micro account for some good training/practice, and maybe even some profit.

Answer
$50.00 is not much to start out with, even trading micro lots.
It can be done, if you dont make the slightest mistake.
Trade 0.01 lots on a micro. Will only be pennies that you win and lose, but it's a start.