1.

The sum of the digits in the unit place of all numbers formed with the help of 3,4,5,6 taken all at a time isA. 18B. 432C. 108D. 144

Answer» Correct Answer - C
Required sum is `3!(3+4+5+6)=6xx16xx18=108`
[ if we fix 3 in the unit place, other three digits can be arranged in 3! Ways similarly for 4,5,6]


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