How is losses per unit sold relevant to anything? Overall profits or losses are what matter. I don't know how much Microsoft made off each one, so I'll be generous and guess $400 average revenue after subsidy payments.

1,000,000,000 - ($400 x 503) = $999,798,800 lost

1,000,000,000 - ($400 x 8810) = $996,476,000 lost

The difference is negligible.