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8. Permutations
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Q27 of 140 Page 276

How many numbers can be formed from the digits 1, 3, 5, 9 if repetition of digits is not allowed?

To find: number of numbers that can be formed from the digits 1, 3, 5, 9 if repetition of digits is not allowed


Forming a 4 digit number:4!


Forming a 3 digit number:4C3 × 3!


Forming a 2 digit number:4C2 × 2!


Forming a 1 digit number:4


So total number of ways=4! + ( 4C3 × 3!) + ( 4C2 × 2!) + 4


=24 + 24 + 12 + 4


=64


More from this chapter

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25

How many 3-letters words can be formed using a, b, c, d, e if

(i) repetition of letters is not allowed?


(ii) repetition of letters is allowed


26

How many 4-digit numbers are there, when a digit may be repeated any number of times?

28

How many 3-digit numbers are there with no digit repeated?

29

How many 3-digit numbers can be formed by using the digits 0, 1, 3, 5, 7 while each digit may be repeated any number of times?

Questions · 140
8. Permutations
1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 1 1 1 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1 2 3 4 5 6 7 1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
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