Question

Find the four-digit number described by these three clues.
1) The first digit is one-third of the third digit.
2) The fourth digit is twice the second digit.
3) The first and third digits add up to twice the sum of the second and fourth digits.

Answer 1

The first digit has to be 1,2,or 3, it can't be anything else.

posibilities:
1x3x
2x6x
3x9x
The second digit can be 1,2,3,4
x2x4
x3x6
x4x8
The final clue lets you determine which digits it is.