10.3 mBTC = 0.0103 BTC
2.4 mBTC = 0.0024 BTC
*** You divide mBTC by 1000 to get the conversion into BTC
Yeah it's pretty easy. It's like the metric system. You can just go and multiply or divide things by 10. I think a lot of people in the US don't even get how awesome and easy the metric system makes things!