HP Prime using user variables with rpn set as input method

[FelixO]

I am trying to ROUND a number to 2 decimal places in the HP Prime using  RPN and  it does not work.   I have tried putting the arguments in the stack, such as:

19.127456

2

ROUND()

ENTER

And the stack is unchanged.

Thanks.

[Joe_Horn]

When a function can have optional arguments, such as the ROUND function which can have an optional second argument, then in RPN you are required to specify how many arguments it should take from the stack, by putting that number in parentheses right after the function.  It looks funny but it works.  So always type ROUND(2) no matter how many digits you're rounding to.  The "(2)" in "ROUND(2)" tells Prime to take 2 numbers off the stack as the arguments for the ROUND function.

Example: To round pi to 4 places in RPN mode, do this:

PI

4

ROUND(2)

An alternative method is to put your Prime in Fixed 4 mode.  Then the ROUND function by itself (with no explicit number of arguments specified) will only take one argument from the stack, and round it to the current display setting.  So, in Fixed 4 mode, the following:

PI

ROUND

returns 3.1416 exactly.

Hope that helps!  Disclaimer: I don't work for HP, but I enjoy playing with their calculators.

[Maké]

Hi!, FeliO:

Welcome, to HP Forum !. 

Syntax:

ROUND(value, [places])

Description:

Rounds value to system display settings. If optional places is given, rounds value to places decimal places. If places is negative, rounds to significant digits instead.

Examples:

ROUND(7.8676,2) returns 7.87

ROUND(19.127456,2) returns 19.13

In RPN ...

1: 19.127456

2: ROUND (2) + ENTER

1: 19.13

[FelixO]

Joe,  thanks it worked fine.

Make, see Joe's post to see how ROUND works in RPN.  What you typed does not work in RPN and returns a Bad argument error. 

Thanks.

[Maké]

Hi!, @FelixO:

Excuse, me by the omission !.

You needed write, as ...

In RPN ...

2: 19.127456

1: 2

ROUND (2) + ENTER

1: 19.13