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Post a New Question | Current Questions | Chat With Live Tutors
Homework Help Forum: 5th grade
Posted by marissa on Tuesday, October 6, 2009 at 8:44pm.
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How many different four-digit numbers can you make from the digits 1,2,3, and 4 if each digit is used only once?
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- 5th grade - Kelly, Tuesday, October 6, 2009 at 9:07pm
1234
1324
1432
1243
1423
1342
2134
2143
2341
2314
2431
2413
3124
3142
3241
3214
3412
3421
4321
4312
4123
4132
4231
4213
24
there are 4 numbers...each can be used only once but 6 different ways
6x4=24
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- 5th grade - Cliff, Thursday, October 8, 2009 at 9:45am
This is a problem class known as permutations. There are 4 choices for your first number (i.e, 1,2,3,4)followed by 3 ways to pick the next number since there are only 3 numbers left. This leaves 2 ways to pick the next number and 1 way to pick the remaining number.
4*3*2*1 = 24
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