Question 1040280
I'm a 4 digit no.<pre>
Let's put 4 spaces for the digits.
_ _ _ _</pre>
My ones digit is three,<pre>
So we put a 3 last:

_ _ _ 3
</pre>
my hundreds digit is two less than the thousands digit,<pre>
So the first two digits are either 9&7, 8&6, 7&5, 6&4, 5&3, 4&2,
3&1 or 2&0

So the number is either

9 7 _ 3
8 6 _ 3
7 5 _ 3
6 4 _ 3
5 3 _ 3
4 2 _ 3
3 1 _ 3
2 0 _ 3
</pre>sum of my digit is 25<pre>We go through them:

9 7 _ 3, since 9+7+3=19, missing digit would have to be 25-19=6  
8 6 _ 3, since 8+6+3=17, missing digit would have to be 25-17=8
7 5 _ 3, since 7+5+3=15, missing digit would have to be 25-15=10,
         impossible, for 9 is the largest digit.  So the others
         require an even larger tens digit.  So they are all 
         ruled out.

So it's either

9 7 6 3 

or

8 6 8 3</pre>My thousands digit is twice the value of one digit,<pre>But the thousands digit of 9763 is 9 which is not twice 
any one digit

And the thousands digit of 8683 is 8 which is not twice 
any one digit
either.

So there is no such 4-digit number.  Tell your teacher 
that he or she has made a mistake and given you an
impossible problem.

Edwin</pre>