SOLUTION: Bert has 10 books and he wants to give 2 of these books to his sister. How many different gifts are possible?

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Question 1118255: Bert has 10 books and he wants to give 2 of these books to his sister. How many different gifts are possible?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Number of combinations of ten things taken two at a time.
C%2810%2C2%29=%2810%29%21%2F%28%2810-2%29%21%2A2%21%29
C%2810%2C2%29=%2810%2A9%2Across%288%21%29%29%2F%28cross%288%21%29%2A2%29
C%2810%2C2%29=90%2F2
C%2810%2C2%29=45