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Question 843766: guess my number: i am less than 25. My ones digit is twice the tens digit, and the sum of my digits is even. What number am I ?
Answer by 1335(25)   (Show Source):
You can put this solution on YOUR website! The number is 24.
There is a long mathematical process, but it is truthfully easier and faster to guess and check.
The number must be two digits with the one being twice the tens and also less than 25. The tens digit can only be a 1 or 2. If the tens digit is a one, two times 1 is two. So the only possible answer can be 12. And 2+1 is 3, an odd number, which can't be correct because it must be even. You now know that the tens digit is 2. 2 times 2 is four. The only number can be 24. 24 is less than 25, the sum of its digits is six, an even number, and its ones digit is twice its tens digit. But once more, it is much faster to use "guess and check"
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