Question

How many 4 digits numbers can be formed using 0,1,2,3,4,5,6,7, if repetition of digits is not allowed

Answer 1

Answer:

Step-by-step explanation:

_ _ _ _

these are the four places in which the numbers must be filled.

the first box can have any of the numbers except 0 . so the number of chances are 7

the second place can be filled with remaining 7 places 0 including

the third place can be filled with 6 digits

the fourth place can be filled with 5 digits

so the number of 4 digit numbers are=7*7*6*5=1470