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| Math Central | Quandaries & Queries |
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Question from Jenny, a student: The units digit of a certain two-digit number is one more than 4 times the tens digit. |
Hi Jenny,
The tens digit has to be small since 1 more than 4 times it is still a one digit number.
The tens digit can't be 0 since then you would only have a 1 digit number.
The tens digit might be 1 and then 1 more than 4 times 1 is 5 so the number would be 15.
The tens digit might be 2 and then 1 more than 4 times 2 is 9 so the number would be 29.
The tens digit can't be 3 or more since, if it were then 1 more than 4 times it would not be a 1 digit number.
Thus the original number is 15 or 29. Which one is it?
Penny
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