How many numbers can be formed from 1, 2, 3, 4, 5 (without repetition), when the digit at the unitâ€

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03 Sep 2020 Permutation and Combination

How many numbers can be formed from 1, 2, 3, 4, 5 (without repetition), when the digit at the unit’s place must be greater than that in the ten’s place?

OPtion

1) 44
2) 55
3) 60
4) 64
5) 63
6) 56
7) 66
8) 58
9) 72
10) None of these

Solution

1 at units place 0 numbers
2 at units 1 at units place 3!
3 at units 1 at units place 3!
3 at units 2 at units place 3!
4 at units 1 at units place 3!
4 at units 2 at units place 3!
4 at units 3 at units place 3!
5 at units 1 at units place 3!
5 at units 2 at units place 3!
5 at units 3 at units place 3!
5 at units 4 at units place 3!

Correct Option: 3 Best Solution (0)