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What two digit numbers are equal to seven time the sum of their digits?
Wiki User
∙ 13y ago
10a + b = 7(a + b)
10a + b = 7a + 7b
3a = 6b
a = 2b
(2,1), (4,2), (6,3), and (8,4) meet these requirements.
So the numbers that are solutions are 21, 42, 63, and 84.
Wiki User
∙ 13y ago
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There are seven possible digits for the first digit and 6 digits for the second (minus one digit for the digit used as the first digit) and 5 options for the last digit (minus one again for the second digit) and then you just multiply them all together to get a total possible combination of 210 numbers that are possible.
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What is the total number of digits in the numbers from 1 to 1000000?
In the numbers 1-9 each number has 1 digit and there are 9 of them, so that's 9.In 10-99 each number has 2 digits, and there are 90 of them: 2x90 = 180There are 900 three digit numbers [100 through 999]: 2700 digits.There are 9000 four digit numbers: 36000 digits.90,000 numbers with five digits: 450,000 digits.900,000 numbers with six digits: 5,400,000 digits.Then 1 number with seven digits: 7 digits.Add them up and you have 5,888,896 digits.
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Can a ten-digit phone number be a legitimate seven-digit number without the last three digits?
No, a 10-digit phone number that is missing the last three digits can not be a legitimate number. In order for a number to work, it must have 3 numbers for an area code and seven digits for the phone number itself. Some telemarketers are now using fake numbers to hide from the people they're calling.
How many different three digit numbers can you form using the digits 1 2 3 5 6 7 and 9 without repetition?
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What seven digit number that comes between one million and two million?
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What is the greatest seven-digit number using four different digits?
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It's not entirely clear from the wording of your question what it is you want to know. Seven is a one-digit number. The sum of its digits is 7. Seven has two factors: 1 and 7. That sum is 8.
What is the probability that a seven-digit phone number has one or more repeated digits?
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9,876,543 is.
