I have multiplied two 3-digit numbers and coded the whole process twice:

In the 1st coding

**
O** replaces an odd digit and

** E** the even.

**
**** OOO
**__* EOE__
OEOE
OOO
__ OEE __
OOOEE

In the 2nd coding

**S** replaces a digit smaller than 6 and

**B** a digit bigger than 5.

**
**** SBB
**__* SSB__
SSSB
SSS
__ BSB __
BBSSB

Try to get my original numbers(digit 9 does not appear in the multiplication) and all other possible solutions, if any.

(In reply to

Not that hard (spoiler) by Steve Herman)

Hi, Steve

1. Assigning a degree of difficulty is a subjective task, usely controversial.

2. I have "tested" my "double code" by asking two of my math-friends to solve it. It took them over 40 minutes each.

3. Apparently both of them are less gifted or less systematic

or both than you.

4. I agree that the solving is easy , once you grasp the fact that all **B&O dtigits are implicitly defined as 7.**

5. Why no one rates this problem?

It is original, thought-provoking and leads to a single solution...

Regards

Ady