Question 939263
Mrs. Rossi wrote the following clues for a Mystery number.

It is a four digit number
<pre>
So suppose it is ABCD
</pre>
The tens are double the ones
The thousands are double the tens
<pre>
C is twice D and A is twice C.
So A is 4 times D, so the number is
either like this 4B21 or like this 8B42
</pre>
the sum of the digits is 19
<pre>
The largest B can be is 9 and 4921 would
only have a sum of digits 16.

So the answer is 8B42 and B has to be 5 to
make the sum of digits 19.
</pre>
What number is it?
<pre>
8542

Edwin</pre>