Currency converter app for Android

So after spending a little bit of time last night playing with a functional prototype I realised it needed changes / additions. The first is the increased spacing and size of the actual converted currency values and including the exchange rate with the currency code. I also tweaked the input background to give it some separation from the rates above to improve the experience when scrolling through rates. The final 2 are additional keypad buttons - the flag will allow you to change your 'base' currency and custom will allow you to input your own rate (for example if the rate has changed since you converted your currency).