



 
Anya, Since the tens digit is double the ones digit and the thousands digit is double the tens digit, the thousands digit is 4 times the ones digit. Thus the ones digit can't be very large since 4 times the ones digit is a one digit number. The ones digit could be 1 since 4 times 1 is 4. The ones digit could be 2 since 4 times 2 is 8. The ones digit can't be 3 since 4 times 3 is 12 and 12 is not a digit. Likewise the ones digit can't be 4, 5, 6, 7, 8 or 9.
I hope this helps,  


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