SOLUTION: How do I find the expression for any two digit number where the tens digit is twice the units digit

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Question 705839: How do I find the expression for any two digit number where the tens digit is twice the units digit
Answer by mouk(232) About Me  (Show Source):
You can put this solution on YOUR website!
Let the unit digit be u then
u = 0,1,2,3,4,5,6,7,8,9

Let the tens digit be d, the tens digit is twice the units digit
then 2u=0,2,4,6,8,10,12,14,16,18
so d=2u must be a digit so d=0,2,4,6,8

so number is 00, 21, 42, 62 or 84
technically 00 is not a two digit number so exclude that from answer