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81 : 8 + 1 = 9, and 9 x 9 = 81.
Here's how to figure: If the 2-digit number is ab,. then the number is equal to 10*a + b. And nine time the sum equals 9*(a + b). Set these two equal and you have:
- 9*a + 9*b = 10*a + b --> 8*b = a.
Knowing that the digits must be in the range 1 through 9: 1 x 8 = 8, and 2 x 8 = 16, so the only possibility is a=8 and b=1.
What else can I help you with?
What is the four digit number whose digits are reversed when multiplied by nine?
Find a four digit number whose digits will be reversed when multiplied by nine?
A certain number has three digits the sum equals thirty six times this number seven times the left digit plus nine equals five times the sum of the first and third number What is the third number?
The answer to this question is at my website aim feliciano980
How many 3-digit palindromic numbers are there?
To be a 3 digit palindromic number, it must be of the form aba.I assume that a 3 digit number must be at least 100 (so that 020 for example does not count as a 3 digit number):a can be any of the nine digits 1-9;for each of these b can be any of the ten digits 0-9Thus there are 9 x 10 = 90 three digit palindromic numbers.
What is the greatest three digit number whose digits have a sum of twelve?
Nine hundred thirty (930) is the highest three digit number whose digits have a sum of 12. 9+3+0=12. Any numbers higher than that will give you an sum greater than 12.
Is the factor of the sum of digits equals 9 or a multiple of 9?
If the sum of the digits of a given number equals nine or a multiple of nine, nine is a factor of that number.
The sum of the digits of a 2-digit number is 10The digit in one's placeis nine times the digit in ten's place Find the number?
-8
What is the highest 9-digit number with no digits alike?
987654321 is the highest nine-digit number with no repeated digits.
What is the four digit number whose digits are reversed when multiplied by nine?
Find a four digit number whose digits will be reversed when multiplied by nine?
How many times does the digit nine appear from 1 to 500?
1 digit number: only 1 number 2 digits number: 18 numbers 3 digits number: 76 So there are 95 numbers containing 9.
What nine-digit number is divisible by 11 and has no repeating digits?
987652431
What is the lowest nine-digit number that can be formed with different digits?
The correct answer is 102,345,678. The number 012,345,678 is considered an eight-digit number; any other rearrangement of the digits, or inserting a 9 in any position, gives a larger number.
A certain number has three digits the sum equals thirty six times this number seven times the left digit plus nine equals five times the sum of the first and third number What is the third number?
The answer to this question is at my website aim feliciano980
What nine digit number is divisible by 11 and has no repeating digits?
There are many possible solutions. One such is 132486970
How many two digit even numbers can be composed from nine digits 1 2 3....9?
The first digit can be any one of the nine digits. For each of those . . .The second digit can be any one of four digits . . . 2, 4, 6, or 8 .Total number of possibilities = (9 x 4) = 36
What's the largest nine digit number with no digits that are the same and the numeral 4 is in the ten million place?
948,765,321
What is the nine digit numbers in 50000 and 3000000?
Oh, dude, you're asking me to count digits now? Okay, let's see. In 50,000, the nine-digit number is 000050000. And in 3,000,000, the nine-digit number is 000300000. Like, who knew counting zeros could be so thrilling, right?
How many strings of four decimal digit have exactly three digit that are nine?
The number of strings of four decimal digits that have exactly three digits which are nine is the number of ways to choose three places to choose the nines multiplied by the number of possibilities for the other digits (because you can put all of the possibilities in an array so that each column has a different way of arranging the nines and that each row has a different set of other digits (because they do not affect each other)). The number of ways to choose the three places to choose the nines is the same as the number of ways of choosing 4-3=1 spot for there not to be a nine. The number of ways of choosing 1 spot where there are 4 spots is 4 (the first, the second, the third, or the fourth). Since there are 9 digits that are not nine, the number of choices for the other digits is 9 (since there is only one digit). Thus, there are 4*9=36 strings of four decimal digits that have exactly three digits which are nine.
