#13 is 3000 because since each T-shirt is $650 and they buy 4 you multiply and get $2600 and since she received 400 dollar change then you add that value to the total cost and get 3000 that means she paid 3000
#14 is a millennium
1 year is 365 days
1 decade is 10 years
1 century is 100 years
1 millennium is 1000 years
So it has to be 1 millennium since 1000 years is the most out of the others