One of the most interesting word problems of all time, which broadened the human intellect in many ways, is the Archimedes cattle problem. There are many excellent books and articles about this--start with the wikipedia page. Also look for "The Sand Reckoner."
Archimedes is trying to explain that "infinity" is (conceptually) much more than just a very large number. He starts with, "There are some, King Gelon, who think that the number of the sand is infinite.."
He poses an innocent sounding word problem about the number of cattle in a herd with various colors. "Compute, O friend, the number of the cattle .. He sets up a word problem that leads to seven linear equations in eight unknowns. The smallest solution is about 50 million. Archimedes says that if you can get this far, then "thou art no novice in numbers." So pat yourself on the back. But then he adds two more equations, which are non-linear, but still seem innocent. One is that the sum of two of the eight unknowns is a square, so $x+y=n^2$. As it turns out, the smallest solution for the size of the herd is then represented as a base-ten numeral with over 200,000 digits. This is an "incomprehensibly" large number. If you can solve this, he says, then "then exult as a conqueror, for thou hast proved thyself most skilled in numbers." The number is more than the number of grains of sand on the earth, indeed much, much more.
So the point here is not that Archimedes is using the equations to solve a practical problem to help a certain person figure out how many cattle are in a herd. Instead, he is setting up a word problem that seems, on the surface, to be rather ordinary and not too ridiculous. But the solution! It is not infinite, but wow..it's a big number. In the Sand Reckoner, Archimedes uses this practical sounding word problem about counting cattle to discuss the size of the universe (3rd century BC!), how many grains of sand would fit into it, how to invent a system to name such an enormous number, and how even enormous numbers are not infinite. It's also a challenge to understand how Archimedes managed to contrive the problem to look innocent, but to have such a large solution. Maybe this mystery just comes down to the fact that he was one of the most brilliant persons to have ever lived.