So yesterday I was doing a lot of trading off site and when I started removing and adding cards from my inventory I was thinking it would be really cool if there was a feature under the inventory to see some of the most recent changes made to quickly make sure I didn't forget to remove or add cards. I feel like that could be a really nice feature so you can double check just to make sure that you didn't miss a card that needed removed without having to search it back up.

When I trade parts of my collection (I only trade locally), I usually create a pseudo-deck where I put all the cards I am trading away. After I actually make the trade, I update each card's count by subtracting the amount I have added to this 'deck'. In most cases this will be just a few copies, so it isn't some high-level math.

Hope this little trick helps you.