Questions & Answers about Pyramiden är fyra tusen år gammal.
Why is the adjective gammal used here instead of gamla, since it comes right after the plural word år?
The adjective gammal describes the subject, pyramiden (an en-word in the singular), not the years. Even though the plural word år sits right next to it, the adjective agreement always jumps back to the noun that is actually being described.
Does Swedish always follow this "number + unit + adjective" order for age and measurements?
Yes, this structure works exactly like in English. You state the quantity (fyra tusen), the unit of measurement (år), and finally the adjective (gammal). You will use this exact same pattern for physical dimensions too, like två meter lång (two meters tall) or fem centimeter tjock (five centimeters thick).
Why does år look like a singular word here when it means "years"?
År is an ett-word (neuter noun) that ends in a consonant. In Swedish, these nouns look exactly the same in their plural indefinite form as they do in the singular. So, ett år (one year) simply becomes fyra tusen år (four thousand years) without adding any plural ending.
Should fyra tusen be written as one word or two?
Both are perfectly fine. You will often see it written as one word (fyratusen), as Swedish loves compound words. However, splitting thousands and hundreds into separate words is also very common and often easier to read.