Abstract:
We consider the comic task of obtaining the number $100$ from a six-digit bus ticket number by placing parentheses and symbols for arithmetic operations between some digits. The solution algorithm for a fixed number is reduced to enumerating all binary trees having exactly six terminal nodes with the signs of operations in internal nodes. For six-digit numbers that do not contain duplicate digits and the digit $0$, the problem has a solution for all numbers except the only number $746189$. It is impossible to obtain a hundred from this strange number $746189$.