# Calculation of complex number

1. May 1, 2013

### Nero26

Hi all,
This is a little problem I'm unable to figure out, in CMPLX mode of my calculator 25i*20i/5i=-100i
But 25i*20i/(5i) = 100i, Here i=sqrt(-1). What is the difference between these two expressions?

2. May 1, 2013

### CompuChip

The difference is that 25i*20i/5i is interpreted as (25i*20i/5)i = (25i*20i/5)*i.
And 25i*20i/5 = -100.

3. May 1, 2013

### Nero26

Thanks a lot for your help, so 'i' is considered as a single complex number.

4. May 1, 2013

### Staff: Mentor

Well, yes, but that's not relevant here.

What Compuchip was talking about was the order of operations. It's the difference between -500/(5i) and (-500/5) * i.

When you write (or enter) -500/5i, the calculator is interpreting this as -500/5 * i.

5. May 2, 2013

### SteamKing

Staff Emeritus
In order to avoid ambiguity in expression evaluation, use parentheses in your expressions.

6. May 2, 2013

### Nero26

Thanks to all. You all are of great help. I think I can learn a lot from PF.