980
20 forties = 800 800 is 200 less than 1000.
There are 1000 millimeters in a meter. There are 1000 meters in a kilometer. Given this information the answer is obvious.
All the prime numbers less than 20 are 2,3,5,7,11,13,17,19
A more formal definition for a number less than 20 could be, "a number x, x < 20" or if you want to express the set of all numbers less than 20 "{x | x < 20}" which is read "the set of all numbers x such that x is less than 20". In interval notation, you can write (-infinity, 20) where "infinity" should be replaced by the infinity symbol.
Usually you can't, because it's less than 1. If I HAVE to write it, I would write 013/20.
20 - 11 = 9
20 grams is less than 2kg. 2kg is 2000 grams.
9999
The prime numbers less than 20 are 2, 3, 5, 7, 11, 13, 17, and 19.
20/1000 = 0.020
20/1000 0.020