July 21, 2015 5:29 PM EDT

Apple posted its third quarter earnings on Tuesday, and, as expected, it didn’t give any precise numbers regarding Apple Watch sales so far. It did, however, give us enough data to make a viable back-of-the-envelope guess.

In its latest earnings reports, Apple has broken out the Units Sold and Revenue Made for several different product categories: iPhone, iPad, Mac, “Services” (iTunes, AppleCare, Apple Pay, etc.) and “Other” (formerly Apple TV, iPod, etc). This time around — Apple’s first earnings report in a post-Watch world — Apple included the Apple Watch in “Other.” That hides the Apple Watch’s performance to some degree — but only a little.

Apple Inc. – Earnings Surprise | FindTheCompany

Apple’s “Other” category has been mostly flat lately, so it’s a safe bet that any spike there is attributable to the Apple Watch. And a spike there was. Revenue in Apple’s “Other” category is up by roughly $1 billion. Unless Apple is suddenly selling way more Apple TVs and Beats headphones, that means Apple made about $1 billion in revenue from Apple Watch sales this quarter. And falling iPod sales means the Apple Watch may have done even better revenue numbers.

Now, it would certainly be nice to use that figure as a starting point to guess the number of Apple Watches sold so far. But that isn’t really possible. Because the Apple Watch’s price differentials are so huge — $349 to start, $18,000 at the high end — it’s hard to estimate any average price point (any significant number of sales at the $10,000 and up range would dramatically skew estimates). So we’ll have to wait until Apple is ready to tell us exactly how many Apple Watches it’s selling to get that information.

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