Question

How many 2-digit numbers can you make without repeating the digits? Numbers like 34 not like 55.

80

81

83

84

Answer 1

81.

Explanation:

The 2 digit numbers without repeated digits is 81. There are 90 two-digit numbers in the decimal system. In 9 of them, both digits are the same number. So, there remain 81 without repetitions.