几 jǐ is used for numbers smaller than ten. It is used with a classifier.
多少 duō shǎo can be used in any situation, i.e. not only for numbers smaller than ten. Usually, it is used without a classifier.
这 | 儿 | 有 | 几 | 个 | 人 | ? |
zhè | ér | yǒu | jǐ | gè | rén | _ |
this | child | have | how many | measure word | person | _ |
here | have, there is | several | person, human being | ? | ||
How many persons are here? |
九 | 个 | 人 | 。 |
jiǔ | gè | rén | _ |
nine | measure word | person | _ |
nine | person, human being | 。 | |
Nine people. |
这 | 儿 | 有 | 多 | 少 | 人 | ? |
zhè | ér | yǒu | duō | shǎo | rén | _ |
this | child | have | many | few | person | _ |
here | have, there is | how many, how much, some | person, human being | ? | ||
How many people are here? |
一 | 百 | 一 | 十 | 个 | 。 |
yī | bǎi | yī | shí | gè | _ |
one | hundred | one | ten | measure word | _ |
100 | one, same, whole | ten | 。 | ||
One hundred and ten. |