Example sentences
zhè这gè个duō多shǎo少qián钱？
How much is this?
nǐ你men们yǒu有duō多shǎo少rén人？
How many people are there?
About this word
多 is "many" and 少 is "few", so the word pairs opposites to cover a whole range of quantity, giving "how many, how much". Chinese builds several quantity questions this way, and the same opposite-pair trick gives 大小 size and 长短 length. Two usage notes. 多少 can sit directly in front of a noun with no measure word (多少人, 多少钱), while 几 needs a measure word and expects a small number. And with a neutral tone, duōshao, it can also mean "somewhat", as in 多少有点累, "a bit tired".
The story behind the character
多
Two 夕 stacked up. Here 夕 isn't evening. It's an old form of 肉 (meat). Two pieces of meat, that's 多. Xu Shen wrote 多, 重也. The ancients measured "a lot" in slabs of meat.
少
Take 小 and chip one more dot off the bottom, and you get 少. The logic is neat: 小 is already small, remove a bit more, and it's "few." It literally reads "small, minus a dot."