Saturday, February 18, 2006

Tony, Kim Vo, Chris and Amalia's word question

question #4: Brian is trying to guess a 2-digit number. So far he knows that the tens' digit is greater than 6, and the ones' digit is odd. He also knows that many two digits are different. How many possibilities are there?
Answer: The answer is 13
Solution: we knew the tens digit was greater than 6 so we used the numbers 7, 8 and 9 foir the tens numbers. We also knew that the ones digit was odd and that you cannot have the same to digits together in one number like the number 77.
The combinations you can have are 71, 73, 75, you cant have 77 though because those two numbers are the same. You can have 79, 81, 83, 85, 87, 89, 91, 93, 95 ,97 but you cant have the number 99. There are 13 combinations in all.


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