On the PDF data sheet we have, I remark that the HP 35s was on RPN mode whit a strange number that I think is a new way to enter a complex number on the stack.

For exemple, the number (5+15i) is enter like this:

enter 15 press "i" key enter 5 press "enter" key.

Then you have 15i5 on the stack!

So this method permit to have a whole complex number in a register.

The HP 35s can now have a new COMPLEX MODE like the HP 15c!

What do you think of that?