Fun facts

►Petronas Towers were the tallest buildings in the world from 1998 to 2004, and now they are still the tallest twin buildings in the world. Location: Kuala Lumpur, Malaysia.

►Did you know that 40 below zero Celsius and 40 below zero Fahrenheit are the same?

My solution to figuring out the ratio the fastest possible, without Internet:

20 C is: 68 F

30 C is: 86 F (the other way around from 68)

40 C is: 104 C (again, there is 4 and 0, just the other way around).

And then I just guess what is in between, knowing that for very 10 Celsius, you get 18 Fahrenheit.