Q. The sum of the digits in the unit place of all numbers formed with the help of 3, 4, 5, 6 taken al, at a time, is
A) 18
B) 108
C) 432
D) 144
Explanation
(b)
Required sum$= 3!(3 + 4 + 5 + 6)$
$= 6 \times 18 = 108$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.