Add Plus Signs
Riddle: How many pluses should we put between the digits of 987,654,321 to get a total of 99, and where?
Answer: (6) 9 + 8 + 7 + 6 + 5 + 43 + 21= 99
(7) 9 + 8 + 7 + 65 + 4 + 3 + 2 + 1= 99
Source: https://www.riddles.com/2276
