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How do I add decimals in Xamarin Forms Entries using C#

For starters I'm very very new to writing code! :)
What I have so far...
So far I've used Xamarin.Forms to create a user interface for a sort of specialized calculator. I'm using a Grid Layout containing: a first column of Labels, a second column of Entries (that I have named in Xaml), and a third column of Steppers (so I can change the entries by typing or using the stepper). These 3 views on each row repeat for several rows with different label text on each row and at the bottom of the Grid Layout I have an Entry for the output.
The problem...
Basically, I want to buy a certain product at different weights and prices...among other criteria....and I want to quickly figure out how much money I'll make at a future possible sale price. Simply put... I'm trying to add/subtract/multiply/divide using Xamarin.Forms Entries. I've looked everywhere and can't seem find anyone giving an example of how to do this. I've tried different methods and usually end with an error of not being able to convert the Xamarin.Forms entry to a string...So I'm back to zero. Can I get an example of a Method where I would be able to add/subtract/multiply/divide 2 Xamarin.Forms Entry views together in the C# code behind? This seems very simple to me...what am I missing??? Is there a thread/article/video somewhere that I haven't found that covers this?? And like I said, I'm very new so the answer is probably very simple.
Thanks in advance!
Steven

Entries deal with strings, not numeric values, so you need to convert them before doing calculations.
var amount = Decimal.Parse(EntryA.Text);
var price = Decimal.Parse(EntryB.Text);
var total = amount * price;
// you can use a format string as an argument to ToString()
// to control the output - ie, how many decimals, commas, etc
LabelTotal.Text = total.ToString();
In a real app you will want to validate the input in case the user enters text instead of a value number (the Parse method will throw an exception if the input is bad);

iText7 Dynamically Set Field Calculation At Run-time

Working with iText7 library version 7.0.2.2 in a c# web application. A PDF document is produced with n-number of dynamically created pages based on the amount of data.
Is there a way to set a field with a calculated formula at run time? So for example, something along the lines of having a subtotal field calculation like
the product of Page1.Lineitem1.qty and Page1.LineItem1.unitprice.

Itext is merely creating the view, the data model feeding it is provided by you.
Furthermore, itext only draws text strings, not numerical types, so it would have to parse those strings back to numbers which can be difficult considering all the ways numbers can be formatted with commas, periods, plus and minus signs, brackets, units,...
And the text pieces you draw with itext are not named.
And itext flushes contents to the output as soon as possible to save memory.
...
So no, itext does not provide support for "the product of Page1.Lineitem1.qty and Page1.LineItem1.unitprice" or similar expressions.

RDLC text overflow behavior

I'm working on converting an older reporting format into RDLC and am running into a problem. In a few edge cases a numeric value overruns its allotted display space -- it's, let's say, '10000%', and I can't just set "CanGrow" to false and let the field truncate since the percent sign must be visible.
In the original reporting format a field too big for its allotted display space just displayed as a bunch of asterisks, so I've got a question in two parts:
1) Is there a way to format the data in RDLC so it displays an alternate string if it runs over a certain value?
2) Is there a way to apply that format for printing only, so that on exporting the data to, say, Excel (with Report.Render) the field will still say '10000%'?

For posterity, what worked here was combining the Globals!RenderFormat field with filtering based on the value. For example
IIF(Globals!RenderFormat.Name Like "excel*" Or
(Fields!Percent1.Value > -10 And Fields!Percent1.Value < 100),
Fields!Percent1.Value, "******")

Formatting text with padding does not line up in C#

I am fairly new to programming and I just wrote a simple application in C# .NET to retrieve information about system drive space. The program functions fine but I'm struggling with formatting the output.
See output:
I'm trying to use padding to get the text to line up in sort of a column format within a rich text box but the output doesn't line up because if there are multiple drives, the drive names are different lengths which throws off the padding. Even if the drive letter comes back one as M: and the other as I: the difference in the size of the letter is enough to throw off the alignment while padding.
I am wondering if there is a way to force each string value to a specific length so the padding is applied evenly or if maybe there's an even better way to format my output. Thank you in advance for your time and let me know if any further information would be helpful!

Note: One of the comments asked an important question, regarding whether the question refers to the System.Windows.Forms.RichTextBox (WinForms) or the System.Windows.Controls.RichTextBox (WPF) control. This answer applies only to the WinForms version of RichTextBox, so if you're using WPF, this doesn't apply.
The most important thing, and this was mentioned in the comments, is that you'll need to use a Monospaced font.
Since you stated you're using a RichTextBox, you'll need to know how to set it to use whatever monospaced font you've chosen.
To do that, you can use the RichTextBox.SelectionFont property.
For more general instructions, refer to this MSDN article: Setting Font Attributes for the Windows Forms RichTextBox Control
Once you set the RichTextBox.SelectionFont property, only text added to the control afterwards will use the specified font. To apply the font to existing text (i.e. you populate the RichTextBox and then change the font to an appropriate monospaced font), take a look at this answer, which tells you precisely what to do.
Once that's done, there remains the simple matter of adding the appropriate amount of whitespace to the end of each string, such that the next piece of data appears at the appropriate position. You'll probably be using String.PadRight, but for more general information about padding strings, check out this MSDN article: Padding Strings in the .NET Framework

Here is string formatting example:
string varOne = "Line One";
double varTwo = 15/100;
string output= String.Format("{0,-10} {1,5:P1}", varOne, varTwo);
//expected output is
//Line One 15 %
where formatting properties in curly brackets are:
{index[,alignment][ :formatString] }

service or strategy to detect if users enter fake names?

Im searching about services/strategies to detect when entered names in forms are spammy, example: asdasdasd, ksfhaiodsfh, wpoeiruopwieru, zcpoiqwqwea. crazy keyboard inputs.
I am trying akismet is not specially for names (http://kemayo.wordpress.com/2005/12/02/akismet-py/).
thanks in advance.

One strategy is having a black list with weird names and/or a white list with normal names, to reject/accept names. But it can be difficult to found it.

you could look for unusual character combinations like many consecutive vowels/consonants, and watch your registrations and create a list of recurring patterns (like asd) in false names
i would refrain from automatically block those inputs and rather mark them for examination

Ask for a real email and send info to connect there. Then get info from the account.
No way is really safe anyway.

If speed isn't an issue, download a list of the top 100k most common names, throw them in an O(1) lookup data structure, see if the input is there, and if not, you could always compare the input to the entries using a string similarity algorithm.
Although if you do, you will probably want to bucket by starting letter to prevent having to perform that calculation on the entire list.