Remember the busy-work worksheets your math teacher assigned you in grade school? Well, if you want that tedious feeling back — without even a single gold star sticker as a reward — then electronics blogger Ken Shirriff has made a video just for you. Watch him “mine Bitcoin” with pen and paper.

I decided to see how practical it would be to mine Bitcoin with pencil and paper. It turns out that the SHA-256 algorithm used for mining is pretty simple and can in fact be done by hand. Not surprisingly, the process is extremely slow compared to hardware mining and is entirely impractical.

There is no simple explanation of how Bitcoin mining works, and you’re not going to find one in less than 500 words. Public-key cryptography and cryptographic hash functions exist in a highly technical context, and Bitcoin uses these in a novel way to secure and confirm transactions on the network. Do not feel bad, cryptography is the strange and spooky realm of the NSA for a reason. But here’s Ken Shirriff manually “mining Bitcoin” at a rate of 2/3rds of a hash a day, which makes him “67 quadrillion times” less efficient than specialized hardware miners. He’s a very inefficient machine:

A Reddit reader asked about my energy consumption. There’s not much physical exertion, so assuming a resting metabolic rate of 1500kcal/day, manual hashing works out to almost 10 megajoules/hash. A typical energy consumption for mining hardware is 1000 megahashes/joule. So I’m less energy efficient by a factor of 10^16, or 10 quadrillion. The next question is the energy cost. A cheap source of food energy is donuts at $0.23 for 200 kcalories. Electricity here is $0.15/kilowatt-hour, which is cheaper by a factor of 6.7 – closer than I expected. Thus my energy cost per hash is about 67 quadrillion times that of mining hardware. It’s clear I’m not going to make my fortune off manual mining, and I haven’t even included the cost of all the paper and pencils I’ll need.

The network processes a block every 10 minutes or so, and it takes him 16 minutes to solve one hash, so by the time he’s 2/3rds of the way done, he needs to start anew.

This massive difficulty rise has made all but the most advanced ASIC miners combined with cheap electricity worthwhile. Unless you have a massive warehouse in China, you lose money.