Семь девяток равны 100
(99 - 9) : 9 + (99 - 9) = 100 99 - 9 = 90 90 : 9 = 10 99 - 9 = 90 10 + 90 = 100 ---------------------------------- 999 : 9 - 99 : 9 = 100 999 : 9 = 111 99 : 9 = 11 111 - 11 = 100