1346
first digit time second digit and second digit times first digit then repeat
If the first digit is 9, you have 9 options (0-8) for the second digit. If the first digit is 8, you have 8 options (0-7) for the second digit. Etc. This leaves you with the arithmetic series: 0 + 1 + 2 + 3 + ... + 9.
The number of 3-digit numbers with no repeated digits is simply 10x9x8 = 720, if you allow, for example, 012 as a 3-digit number. There are 10 digits, any of which might be the first digit. The second digit can be any digit except the digit that was used for the first digit, leaving 9 possibilities. The third digit then has 8 possibilities, since it can't be the same as the first or second digit. The actual number of possible area codes will be lower, because there are additional restrictions on the number combinations for a valid area code. For example, in North America (USA, Canada, etc.), the first digit of an area code cannot be 0 or 1 and the middle digit cannot be 9.
0 is the ten's digit of the first odd number.
1 3 4 9
Not necessarily. Consider 444. The digits are not different. The first and second digits are not multiples of 3 The first digit is not greater than the second digit. In spite of all that, 444 is a 3-digit number
1349
208
182
89
Multiply the three-digit number by the one's digit, or last digit, of the two-digit number. That is your first part. Now multiply by the second-to-last digit, or ten's digit, and multiply the result by 10. That is your second part. Add the two parts and that is your answer.
4284
If you mean digit, the answer is NO.
27
Look for the first digit that is different. In this case, the first digit after the decimal point. The number that has the larger digit in this position, is larger. If the first digit is the same, compare the second digit with the second digit, the third digit with the third digit, and so forth, until you find a difference.
2.3
Just compare the digits one by one: compare the first digit after the decimal point with the first digit of the other number, the second digit with the second digit, etc., until you find a digit that is different.