George W.
asked • 03/14/16Wats is my number
I’m thinking of a ten-digit integer whose digits are all distinct. It happens that the number formed by the first n of them is divisible by n for each n from 1 to 10. What is my number?
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1 Expert Answer
Mark M. answered • 03/14/16
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Mathematics Teacher - NCLB Highly Qualified
I shall, even without a promise of pizza, make a start
The first digit must be 1, it is the only number divisible by 1.
The tenth digit must be 0, since the number is divisible by 10.
The fifth digit must be 5, since numbers divisible by 5 must end in either 5 or 0 that is already used.
Now work out the rest and win some pizza!
George W.
Tat doesn't help me to understand the question tho
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03/14/16
Mark M.
The first digit must be divisible by 1.
The number made by the first two digits must be divisible by 2.
The number made by the first three digits must be divisible by 3.
The number made by the first four digits must be divisible by 4.
This pattern continues for all ten digits.
Did I make sense?
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03/14/16
George W.
So ur saying 3 is not divisible by 1?
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03/14/16
Mark M.
Rethinking, yes, any of the nine digits (cannot be 0) could be the first number.
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03/14/16
George W.
Yah tanks for ur help
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03/14/16
Mark M.
You are welcome.
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03/15/16
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Mark M.
It is one proposed by Pizza Hut.
If I solve, do I get some of your pizza?
03/14/16