Calculators TI-30X Pro - Decimals Rounding issue

[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?

Thanks i advance for your answers and help!

 

[DrClaude]

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

 

[Sakitumi]

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

Thank you for your reply.
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.

 

[DrClaude]

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

 

[Sakitumi]

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

1.732050808

 

[DrClaude]

1.732050808

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

 

[Sakitumi]

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

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.

 

[Sakitumi]

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

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

 

[DrClaude]

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.

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.

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.

 

[Sakitumi]

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.

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.

 

[DrClaude]

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.

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.

 

[Vanadium 50]

It uses 13 digits internally and displays 10.

 

[Sakitumi]

Thank you guys! I need a new calculator then.