Question

How many 7-digit number can be formed using the digits 1,2,0,2,4,2 and 4?

Answer 1

Answer:

1152 numbers

Step-by-step explanation:

for the 7th place there are : 3 numbers ( 0 cannot be used as the. it will become a 6 digit number )

for the 6 th place there are : 4 numbers

for the 5 th place : 4 numbers

for the 4th place : 4 numbers

for the 3rd place : 3 numbers

for the 2nd place : 2 numbers

for the last place : 1 number

different combinations : 3x4x4x4x3x2x1 = 1152 numbers

Answer 2

THE ANSWER IS 360.

Step-by-step explanation:

There are 7 digits 1, 2, 0, 2, 4, 2, 4 in which 2 occurs 3 times, 4 occurs 2 times.

Number of 7 digit numbers = 3!×2!/7! =420

But out of these 420 numbers, there are some numbers which begin with '0' and they are not 7-digit numbers.

The number of such numbers beginning with '0' = 3!×2!/6! =60

Hence, the required number of 7 digit numbers = 420 - 60 = 360.