Interesting but can it do more than addition? Also it doesn't seems to have 100% accuracy.

Yeah. I only trained addition. Actually exploring the impact of training a net to perform a range of operations on the minimum plausible neuron count would be quite interesting

I don’t see any reason why it would be significantly harder to do, however

You’re right about accuracy. I didn’t let the model train enough to push the error low enough to guarantee exact results over the input range. But then again this was designed as a toy experiment, not something people should rely on