Question

(1) 120
124
Using any four digits at a time out of 3, 4, 5, 6, 7 only once, how many different
numbers can be made?
(1) 120
(2) 124
(3) 130
(4) 140​

Answer 1

Answer:

Given numbers are 3, 4, 5, 6, 7

(i) Excluding 3,

» Remaining four digits can form 4! numbers.

Similarly for (ii), (iii), (iv) and (v)

» 4! numbers can be formed in each case.

Therefore, total numbers can be formed

= 4 × 4! = 5 × 24 = 120