You know, people often complain about goal shifting in AI. We hit some target that was supposed to be AI (or even AGI), kind of go meh - and then change to a new goal. But the problem isn't goal shifting, the problem is that the goals were set to a level that had nothing whatsoever to do where we "really" want to go, precisely in order to make them achievable. So it's no surprise that when we hit these neutered goals we aren't then where we hope to actually be!
So here, with your example. Basic software programs can multiply million digit numbers near instantly with absolutely no problem. This would take a human years of dedicated effort to solve. Solving work, of any sort, that's difficult for a human has absolutely nothing to do with AGI. If we think about what we "really" mean by AGI, I think it's the exact opposite even. AGI will instead involve computers doing what's relatively easy for humans.
Go back not that long ago in our past and we were glorified monkeys. Now we're glorified monkeys with nukes and who've landed on the Moon! The point of this is that if you go back in time we basically knew nothing. State of the art technology was 'whack it with stick!', communication was limited to various grunts, and our collective knowledge was very limited, and many assumptions of fact were simply completely wrong.
Now imagine training an LLM on the state of human knowledge from this time, perhaps alongside a primitive sensory feed of the world. AGI would be able to take this and not only get to where we are today, but then go well beyond it. And this should all be able to happen at an exceptionally rapid rate, given historic human knowledge transfer and storage rates over time has always been some number really close to zero. AGI not only would not suffer such problems but would have perfect memory, orders of magnitude greater 'conscious' raw computational ability (as even a basic phone today has), and so on.
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Is this goal achievable? No, not anytime in the foreseeable future, if ever. But people don't want this. They want to believe AGI is not only possible, but might even happen in their lifetime. But I think if we objectively think about what we "really" want to see, it's clear that it isn't coming anytime soon. Instead we're doomed to just goal shift our way endlessly towards creating what may one day be a really good natural language search engine. And hey, that's a heck of an accomplishment that will have immense utility, but it's nowhere near the goal that we "really" want.