Questions & Answers about Onko sinulla yhdet kiikarit?
Why use the plural yhdet instead of just yksi?
The word for binoculars, kiikarit, is a pluralia tantum word, meaning it only exists in the plural form when referring to this specific object (just like in English). To count nouns that are always plural, you must use plural numerals. So, one pair is yhdet.
If I just said Onko sinulla kiikarit?, wouldn't that mean the same thing?
Close, but there is a slight difference. Onko sinulla kiikarit? just asks if you have binoculars in a general sense. Adding yhdet specifically asks if you have exactly one pair of binoculars, emphasizing the quantity.
Normally numbers force the following noun into the partitive case. Why isn't it yhdet kiikareita?
That rule only applies to singular numbers (like when you say kaksi autoa). Plural numbers behave differently: they work like regular adjectives and simply match the case of the noun. Because this is a standard possession sentence for a complete item, the noun is in the nominative plural (kiikarit), so the number matches it exactly as yhdet.
Does the singular word kiikari exist at all?
Yes, but it usually means a spyglass, telescope, or monocular (a device with only one lens). Because standard binoculars have two lenses, Finnish treats them as a pair, hence the plural kiikarit.