How do I calculate Margin?

Margin is calculated as Positions Value in account currency terms, divided by Leverage. 

Example A: 
Trading account currency: EUR
Currency pair traded: EUR/USD at 1.34500
Lot Size traded: 1.00 (100,000 units)
Leverage: 1:200 Margin = EUR100,000 / 200 = EUR 500

Example B: 
Trading account currency: USD
Currency pair traded: EUR/USD at 1.34500
Lot Size traded: 1.00 (100,000 units)
Leverage: 1:200 Margin = EUR100,000 * 1.34500 / 200 = USD 672.50