(1 pt) How many 4-digit numbers can be formed using the digits 0 and 1?

Question

How many 4-digit numbers can be formed using the digits 0 and 1? Repeated digits are allowed.

Answer 1

For the first digit you are picking from 2 digits.

For the second digit you are picking from 2 digits.

For the third digit you are picking from 2 digits.

For the fourth digit you are picking from 2 digits.

 

2*2*2*2=16 4-digit numbers

 

0000

1000

0100

0010

0001

0110

1001

0011

1100

0101

1010

1110

0111

1011

1101

1111

Answer 2

1000, 1001, 1010, 1011,  1100, 1101, 1110,