# 1/e do not lie

Arguably the tastiest cookie sold in the market today is the famous “37% chocolate chips cookie”, also dubbed the “1/e cookie” by fellow mathematicians and other geeks (as to why that is – in a future post, maybe). Its awesome power comes from a powerful combination of cookie dough and chocolate. Lots of chocolate, actually – 37%.

But I am always suspicious of consumer products. Almost every product says that it’s the tastiest, of highest quality, or the best in the game; some advertising must be false. Despite my great love for these cookies, I could not trust their self proclaimed high chocolate percentage. When you eat them, it always seems like there is much less. I had to find out by myself if the claim is true – is more than a third of the cookie really made of chocolate?

I set up a little experiment. Given a cookie, all I have to do is separate the chocolate from the dough. Once I extract the chocolate, I can weigh it and compare the result to the weight of a single cookie. If the result is 37% for chocolate, or 63% for dough, they pass the test.
For this noble purpose, 6 brave cookies were sacrificed. They will forever be remembered as those who willingly gave away their tasty essence in the name of science.

Separation was achieved through a thorough shower. Cookie dough is soluble in water, while chocolate isn’t, so using strong jets and a kitchen sieve, we can wash away all the dough and leave the precious chocolate intact. But first, we have to break the cookies up, for ease of extraction.

I don’t have any pictures of the actual sieving, but you can bet that it had some intense cookie dough action. If you want to repeat this experiment yourself, it may be tempting to use warm water in order to speed things up, but this melts your chocolate, causing it to escape through the sieve. Also be sure to use a sieve with small holes, else the fine chocolate chips will escape. All in all, after several minutes of gold-sifting-like exercise, we remain with only raw chocolate. This has to be dried up, otherwise the excess water will tilt the scales.

Resisting the temptation to gobble everything up, I finally weighed the end product.

All six cookies together weighed 118 grams. The chocolate alone – 41 grams. A quick calculation gives us: 41/118 = 0.3475, only off by 2.25%. Given that fine grains of chocolate might have escaped through the sift, this is not at all a bad result.
It seems that 1/e cookies hold up to their promise, and indeed deliver 37% of chocolate delight.