# Calculators TI-30X Pro - Decimals Rounding issue

1. Apr 16, 2018 at 6:43 AM

### Sakitumi

Hi guys,
I am using a Texas Instruments TI-30X Pro calculator.
I add 599,944,263.55 to 8,404,167.32 and get 608,348,430.9 instead of 608,348,430.87. It seems it rounds the decimals on its own.
What am I missing?

2. Apr 16, 2018 at 7:13 AM

### Staff: Mentor

Isn't the display limited to 10 digits? In that case, then it will indeed round the result to 10 digits.

3. Apr 16, 2018 at 7:39 AM

### Sakitumi

Now I quote from the User Manual that came with the product:

[poly solv] An entry or menu displays beyond 16 digits.

I asume it should display the result without rounding it.

I guess the limit in digits display goes beyond the 10 digit you normally find in so called market calculators.

4. Apr 16, 2018 at 7:42 AM

### Staff: Mentor

What is the answer to $\sqrt{3}$?

5. Apr 16, 2018 at 7:44 AM

### Sakitumi

1.732050808

6. Apr 16, 2018 at 7:50 AM

### Staff: Mentor

So the calculator is indeed rounding to 10 digits ($\sqrt{3} = 1.732\,050\,807\,568\,877\ldots$)

7. Apr 16, 2018 at 7:54 AM

### Sakitumi

Then in my hundreds of millions arithmetic I should get Syntax Error or similar error considering the, I quote:

EQUATION LENGTH ERROR — An entry exceeds the digit
limits (80 for stat entries or 47 for constant entries); for
example, combining an entry with a constant that exceeds the
limit.

I am confident I am doing something wrong. I tried the same calculation on a Chinese simple calculator and it works perfectly fine. The price and brand comparison is no match and not the subject to my inquiry.

8. Apr 16, 2018 at 7:56 AM

### Sakitumi

But probably you are right and the producer missed filling the "10 digit limit" information in the User's Manual.

9. Apr 16, 2018 at 8:01 AM

### Staff: Mentor

Internally, the calculator is probably keeping more digits than the 10. After having got the result for $\sqrt{3}$, you can multiply it by 2, and you will probably find a number ending in 5, not in 6.
I am not sure what you are doing, but it looks like you are entering something that is too long. Check what you are actually typing on the keypad.

10. Apr 16, 2018 at 8:16 AM

### Sakitumi

I quote from the User Manual:
EQUATION LENGTH ERROR — An entry exceeds the digit
limits (80 for stat entries or 47 for constant entries); for
example, combining an entry with a constant that exceeds the
limit.

It should display pass by the 10 digit limit, shouldn't it? Instead it rounds it.

11. Apr 16, 2018 at 8:31 AM

### Staff: Mentor

The way I read, is that if you try to enter a constant with more than 47 digits, it will not take it. I would be extremely surprised if the calculator could actual do calculations on a 47-digit number. My guess is that internally, it must use 12-16 digits at most.

12. Apr 16, 2018 at 7:14 PM

Staff Emeritus
It uses 13 digits internally and displays 10.

13. Apr 17, 2018 at 9:35 AM

### Sakitumi

Thank you guys! I need a new calculator then.