10
You can only have one choice, the number 4 as the hundred digit and also one choice, the number 5 as the units digit. However, you can have any integer from 0-9 as the hundreds digit.
The number of combinations is thus 1 x 10 x 1 = 10.
The digit after the hundreds digit is 9 which is greater than or equal to 5, so add 1 to the hundreds digit: 14494 → 14500 to the nearest hundred.
30,25,15,20, or 10.
93 and 42
5
89 x 90 = 8010 which are two consecutive two digit numbers that equal 8010.
There are five such numbers.
The digit after the hundreds digit is 9 which is greater than or equal to 5, so add 1 to the hundreds digit: 14494 → 14500 to the nearest hundred.
Write them as decimals, and compare. If the first digit of two numbers is equal, compare the second digit; if the second digit is equal, compare the third digit, etc.
It is 275
These numbers are selections from the numbers from 100 to 999. That's 9 choices for the first digit. Each time, the second digit has 9 choices (0 to 9 excluding the hundreds digit), and then the last digit has 8 choices. Total is then 9x9x8 = 648
11 and 18
2,4,6,8,10,12,14,16,18
30,25,15,20, or 10.
275 = Ones275 = Tens275 = Hundreds2 + 5 = 7275
93 and 42
There are no three-digit numbers that equal 17. In fact, there are no numbers with more or less than two digits that equal 17. In fact, in the whole infinite supply of numbers, there is only one single number that equals 17. That number is . . . . . . . 17 .
Two (or four) digits added together cannot equal 42. Two-digit numbers multiplied together cannot equal 82.