Multiple currency trading calc

I've a question on trading multiple currencies at the same time on the same account.

How to and what is max extreme without getting a margin call?

For example:

I open multiple positions on EJ EU GJ and GU.

My account is 10K

My SL for all is 30 pips

My max risk for trade is 2%

With the above in mind position size if 1 standard lot each ccy pair, therefore at the same time I have 4 standards open.

I'm so crap at maths

You'll have enough margin to hold those 4 positions. But your risk will be higher than 2%. With 30 pips stop loss you'll be risking 3% for EUR/USD and GBP/USD positions and even more for EUR/JPY and GBP/JPY positions.