brojka

1. figure; number
   Brojke pokazuju da je nezaposlenost pala. — The figures show that unemployment has fallen.
   Tražili su okruglu brojku od milion dinara. — They asked for a round figure of a million dinars.
2. digit; numeral
   Lozinka mora da sadrži bar jednu brojku. — The password must contain at least one digit.

"Brojka" usually refers to a specific figure or statistic, while "broj" is the general word for number.