Comment 6 for bug 1226738

"Entering the above into the calculator actually displays the calculation as:

   9
* 9
- 0
= 72

Which is clearly wrong. If you're going to implicitly add numbers to the calculation, you need to actually display them."

Agreed. It doesn't make sense to consider the operator if the user hasn't input any number after that.

"I would expect that after entering an operand such as '+', if I then hit a different operand like 'x' it would change the operand, because I've just changed my mind."

Agreed.