Actually, it is perfectly fine to say twice as hot, half the temperature, but you need to put the temperature in an absolute scale first, like Kelvins.
And just to add to that: Infinity is not a number, it’s a concept.
*Anyone * can find or get a penny. Therefore, it is best to assume I have one penny, and you have $100. Hence you have 10,000 times more money than I do.
But what if you still owe $200k on your mortgage when you find that penny?