Warren Buffett turned 90 this past weekend, and Bill Gates marked the occasion with a blog post and video honoring his friend. Gates was full of accolades, but perhaps this is the most important one: He says Buffett taught him the value of being friends with people you admire.

Here's a look at how Gates is celebrating all things Buffett.

1. A (supposedly) homemade birthday cake

Buffett's 90th birthday seems even more worthy of celebration when you consider that he shouldn't have gotten there at all, given his eating habits, which involve lots and lots of sugar, trans fats, and other things doctors tell you to avoid if you hope to live to a ripe old age. 

"Warren has the mental sharpness of a 30-year-old, the mischievous laugh of a 10-year-old, and the diet of a 6-year-old," Gates writes. "He once told me that he looked at the data and discovered that first graders have the best actuarial odds, so he decided to eat like one. He was only half-joking." And so, Gates writes, he created this video to honor Buffett's dietary choices.

 

It's all a big fake, of course. Gates famously can't cook. (Here he is struggling through a very basic baked chicken recipe.) Besides, the video seems to show him using a raw egg to make buttercream frosting. If you know anything about frosting, you know you don't put a raw egg in it, and serving such a thing to Buffett would risk infecting his nonagenarian friend with salmonella. 

2. Buffett by the numbers

Gates says that both he and Buffett love math and numbers, so he decided to list some pertinent numbers in his blog post. For instance, 30, the number of years Buffett has presumably spent sleeping if he's been getting the recommended eight hours every night. And 10,649, the number of days the two have known each other. (That's 29 years, one month, and 25 days to you and me.)

Most touchingly, two -- the number of phone numbers Gates says he has on speed dial. One is his wife Melinda's, the other is Buffett's.

3. Buffett's advice on choosing friends

Gates has many nice things to say about Buffett, but perhaps the nicest is this: "Of all the things I've learned from Warren, the most important thing might be what friendship is all about. As Warren himself put it a few years ago when we spoke with some college students, 'You will move in the direction of the people that you associate with.'"

With that in mind, Buffett advised the students, "Make some good friends, keep them for the rest of your life, but have them be people that you admire as well as like." In his friendship with Buffett, Gates writes, he has very much followed that advice.