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A window through the walls of our classroom. This is an interactive learning ecology for students and parents in my Applied Math 40S class. This ongoing dialogue is as rich as YOU make it. Visit often and post your comments freely.
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4 comments:
Mr.K
I don't understand the homework question on slide 7 . Did you count # 0 when the last number is 5 ? I think it should be 8 . 10 . 1=80
???
@cowmilk: We are trying to find how many 3 digit numbers there are ending in 5 AND all the digits CAN repeat. SO:
9 10 1
1st 2nd 3rd
3rd digit: must be "5", only 1 way to do this.
1st digit: can be anything except zero (1, 2, 3, 4, 5, 6, 7, 8, 9), 9 ways to do this.
2nd digit: can be any digit including zero (0, 1, 2, 3, 4, 5, 6, 7, 8, 9), 10 ways to do this.
Does that make sense?
yap ..thank you ^^
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