Q. Let 1, 2, 3, 4 are four numbers. How many numbers can be made using all four numbers?
A) 1
B) 3
C) 2
D) 64
Explanation
(d)
Given four numbers 1, 2, 3 and 4
Number of numbers of one digit$= {\ ^{4}P}_{1} = 4$
Number of numbers of three digit numbers$= {\ ^{4}P}_{3} = 24$
Number of numbers of three digit numbers$= {\ ^{4}P}_{3} = 24$
And four digit numbers$= {\ ^{4}P}_{4} = 24$
$\therefore$ Total number of numbers that can be formed
$= 4 + 12 + 24 + 24 = 64$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.