How many 3-digit numbers have digits that never decrease from left to right (for example 112 or 359)?

0 cannot appear (it would have to come first). Choose 3 digits from 1–9 with repetition allowed; each choice gives one number: ${}^{9+3-1}{C}_3={}^{11}{C}_3=165.(84={}^9{C}_3$ forbids repeated digits.)