Условие:

59 + 1
701
1001
10010
60 + 10
60 + 30
99 + 1
991

59 + 1 = 60
701 = 69
1001 = 99
10010 = 90
60 + 10 = 70
60 + 30 = 90
99 + 1 = 100
991 = 98