Learn Polish: W komisji było wczoraj siedmiu polityków. - There were seven politicians in the commission yesterday.

This is the main rule for numbers 5 and above! When a subject has a number from 5 onwards, the group is treated as a single quantity rather than multiple individuals. In the past tense, this means the verb must be in the third-person neuter singular form (było).

Why is the number seven written as siedmiu instead of the standard siedem?

Because polityk (politician) is a masculine personal noun. In Polish, numbers 5 and above take a special form (like siedmiu, pięciu, dziesięciu) when counting men or mixed-gender groups. If you were counting objects or women, you would use the standard form: siedem stołów (seven tables) or siedem kobiet (seven women).

Why is the noun polityków in the genitive case?

Numbers 5 and above always force the noun they are counting into the genitive plural. You can think of it as saying a group of seven of politicians.

I see w komisji. Why does komisja end in -ji here?

The preposition w (meaning in or at a location) requires the locative case. For feminine nouns ending in -ja (like komisja), the locative ending becomes -ji.