Learn Russian: В театре тысяча зрителей, а билет стоит пятьдесят монет. - There are a thousand spectators in the theater, and a ticket costs fifty coins.

In Russian, numbers ending in 5 through 0, such as 50, and quantity words like тысяча (a thousand) require the noun that follows them to be in the genitive plural. Since we have тысяча (1000) and пятьдесят (50), both зритель (spectator) and монета (coin) change to their genitive plural forms: зрителей and монет.

Why does the word for fifty (пятьдесят) have a soft sign in the middle but not at the end?

Numbers from 50 to 80 are compound numbers formed by combining two parts (like 5 and 10). The first part keeps its soft sign (пять), but the second part (десят) drops it. So, fifty is written as пятьдесят, not пятьдесять.

Is тысяча considered a number or a noun here?

тысяча behaves exactly like a regular feminine noun ending in -а. When used in the nominative or accusative case to count things, it always forces the counted objects into the genitive plural, which is why we say тысяча зрителей.

Why use а instead of и for "and" in this sentence?

The conjunction а is used here because the sentence is shifting focus between two separate but related facts: the number of people versus the price of a ticket. While и simply joins similar things together, а is used to smoothly shift the topic, often translated as "and" or "whereas".