SOLUTION: A 4-digit car number has the following: 3rd digit and 2nd digit are d same.. Doubling 1st gives u 4th digit. Doubling first 2 digits gives u next 2. Find the car no..? T

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Question 761081: A 4-digit car number has the following:
3rd digit and 2nd digit are d same..
Doubling 1st gives u 4th digit.
Doubling first 2 digits gives u next 2.
Find the car no..?
True test to ur intelligence....try dis 
Found 2 solutions by ramkikk66, htmentor:
Answer by ramkikk66(644) (Show Source):
You can put this solution on YOUR website!
Answer is
Brute force way of trying all possible combinations for the middle two digits and eliminating them logically.
:)

Answer by htmentor(1343) (Show Source):
You can put this solution on YOUR website!
Let the 2nd and 3rd digit = t
Let f = the 1st digit
Then the last digit = 2f
So the number looks like: f t t 2f
Doubling the first two digits gives the last two. Treat each as a two digit number.
Then we can write this in equation form as
2(10f + t) = 10t + 2f
20f + 2t = 10t + 2f
18f = 8t
9f = 4t
t = (9/4)f
Now the number looks like: f (9/4)f (9/4)f 2f
For the digits to be integers from 0 to 9, f must equal 4. Any other value gives a non-integer digit or a digit > 9.
So the solution is 4 9 9 8