We call a number special if every digit in the number either is a 1 or borders a 1. For example, 11111, 13, 141, 1441, 515151, and 101 are all special, but 10001, 222, 122, and 1333 are not special.

Any two-digit number beginning with a 1 is unique (and all special numbers have at least one 1). There are nine 2-digit numbers with the ones digit 1, and nine more 2-digit numbers with the tens digit 1 (except for 11, which has already been included because its ones digit is 1). As a result, there are 9+9=18 exceptional two-digit numbers.

What is special number called?

When the total of the factorial of digits equals the original number, the number is known as a special number (given number).

Another special number is to add twice the tens digit to the units digit, then add this to the product of the digits to go back to the original number.

So you already know that the second digit in a two-digit number is always 8.

If all of the digits in a number are the same, we call it a special number. Special numerals include 1, 11, 1111, and so on. The special numbers are counted in the following order: 1, 11, 111, 1111, 2, 22, 222, 2222, 3, 33, 333, 3333, and so on.

special numbershave at least one 1). There are nine 2-digit numbers with the ones digit 1, and nine more 2-digit numbers with the tens digit 1 (except for 11, which has already been included because its ones digit is 1). As a result, there are 9+9=18 exceptional two-digit numbers.special numbercalled?special number(given number).special numberis to add twice the tens digit to the units digit, then add this to the product of the digits to go back to the original number.Special numeralsinclude 1, 11, 1111, and so on. The special numbers are counted in the following order: 1, 11, 111, 1111, 2, 22, 222, 2222, 3, 33, 333, 3333, and so on.special numbersvisit: