Q:

Trying to multiply by 100 or 100 each row and column in CSV using PowerShell

Here is the .txt example tab delimited file as it starts out:
CH00-03 CH00-04 CH00-06 CH00-07 CH00-08
°F  °F  °F  °F  °F
1.1120e+002  1.0040e+002     4.0208e+002     4.4312e+002     4.5428e+002
2.3378e+002  2.3810e+002     2.4386e+002     2.5376e+002     4.1126e+002
2.6726e+002  2.5970e+002     2.5790e+002     2.5880e+002     2.6294e+002
-5.8662e+003    -5.8662e+003    -5.8662e+003    -5.8662e+003    -5.8662e+003

I am running this code to change it to a CSV removing the E+ as well:
$DataPath = 'C:\Test'
$DataName = '\*.txt'
$DataTemp = '\Tempfile.csv'
$NewData = '\Complete.csv'

$DataStream = $DataPath + $DataName
$TempStream = $Datapath + $DataTemp
$NewStream = $DataPath + $NewData
#$DataContent = $DataName

$DataContent = Get-Content -Path  "$DataStream" -Raw

$Data1 = $DataContent -replace '[E+]','' 
$Data2 = $Data1 #Required as for some reason no data comes out if not passed through another variable.
ECHO $Data2 > $TempStream 

IMPORT-CSV -Delimiter "`t" -Header ('Column1','Column2','Column3','Column4','Column5')  -Path $TempStream | Export-Csv $NewStream -NoType

then I was grabbing the data from the $NewStream to multiply by 100 or 1000 depending on the last digit after removing the E+
at the moment I am trying to get the multiplication to work before choosing what to multiply by here is some trial and error failures:

test to split data and digits.

$import = get-content $NewStream
$import | select -First 3 | Set-Content $Header
$import | Select-Object -Skip 3 | Set-Content $CSVOUT
$NewImport = Get-Content $CSVOUT

tried this was not sure if this was close or not.

$NewStream | foreach-object {$_ * 100} | Set-Content "C:\Test\Testing6.csv"

tried this however I feel this is not able ot work with what I got for some reason 

$arr = $DataContent
for($i = 0; $i -lt $arr.Length; $i++){
   $arr[$i] = $arr[$i] * 100
}
ECHO $arr > "C:\Test\Testing6.csv"

also tried it with this
$arr = $DataContent2
for($i = 0; $i -lt $arr.Length; $i++){
   $arr[$i] = [float]$arr[$i] *= 100
ECHO $arr > "C:\Test\Testing6.csv"
}

the $NewStream looks like this
Column1,Column2,Column3,Column4,Column5
CH00-03,CH00-04,CH00-06,CH00-07,CH00-08
°F,°F,°F,°F,°F
1.1120002,1.0040002,4.0208002,4.4312002,4.5428002
2.3378002,2.3810002,2.4386002,2.5376002,4.1126002
2.6726002,2.5970002,2.5790002,2.5880002,2.6294002
-5.8662003,-5.8662003,-5.8662003,-5.8662003,-5.8662003

I am trying to multiply all these by 100 or 1000 based on the last number per number but simply always run into different errors no matter what I try. 
I think I may have made it much harder than it needs to be please help anything would be welcome to get this working correctly.  I am open to other windows programming languages as well:)
EDIT:
Thank you Mathias, you got me the rest of what I needed to finish the script. 
The "`t" did not seem to work, however as seen below I found a way to work with it.
Here is the end result that works for me:
#Setup to easily change Data Path.
$DataPath = 'C:\Test'
$DataName = '\*.txt'
$DataTemp = '\Tempfile.csv'
$NewData = '\Complete.csv'
$FinalData = '\Final.csv'

#Path Concatenation.
$DataStream = $DataPath + $DataName
$TempStream = $Datapath + $DataTemp
$NewStream = $DataPath + $NewData
$OUTCSV = $DataPath + $FinalData

#Getting Content
$DataContent1 = Get-Content -Path  "$DataStream" -Raw

#Because Get-Content does not work when introduced into IMPORT-CSV directly as a variable it needs a file changed to csv.  all other ways would give me dupe header errors.
$DataContent1 > $TempStream

#Because "`t" does not work in Convertfrom-csv or Convertto-csv.  Also because of Dupe header errors, this helps the most in eliminating them.

IMPORT-CSV -Delimiter "`t" -Header ('Column1','Column2','Column3',
'Column4','Column5','Column6','Column7','Column8','Column9','Column10',
'Column11','Column12','Column13','Column14','Column15','Column16',
'Column17','Column18','Column19','Column20','Column21','Column22',
'Column23','Column24','Column25','Column26','Column27','Column28',
'Column29','Column30')  -Path $TempStream | Export-Csv $NewStream -NoType

#Grabbing the new content.
$DataContent2 = Get-Content -Path  "$NewStream" -Raw

#This is the Scientific Notation conversion to Decimal.
$DataContent2 = [regex]::Replace($DataContent2, '(-?\d+\.\d+e\+\d+)', {param($m) $m.Value -as [double]})

#This creates the File I needed:) 
$DataContent2|ConvertFrom-Csv -delimiter ","|Export-Csv -Path $OUTCSV -NoTypeInformation

#To delete the CSV files used to build the Final CSV

DEL $TempStream
DEL $NewStream

A:

You don't need to parse these numbers manually, PowerShell supports scientific notation!
PS C:\> '4.0208e+002' -as [double]
402.08

So all you need to do is convert to values to a numerical type! You can use the Regex.Replace() method to pass a scriptblock that converts numbers in scientific notation like so:
$DataContent = Get-Content -Path  "$DataStream" -Raw

$DataContent = [regex]::Replace($DataContent, '(-?\d+\.\d+e\+\d+)', {param($m) $m.Value -as [double]})

$DataContent will now look like this for the sample input you posted:
CH00-03 CH00-04 CH00-06 CH00-07 CH00-08
°F  °F  °F  °F  °F
111.2   100.4     402.08     443.12     454.28
233.78  238.1     243.86     253.76     411.26
267.26  259.7     257.9     258.8     262.94
-5866.2    -5866.2    -5866.2    -5866.2    -5866.2

Now just convert from TSV to objects and export to CSV again with the default delimiter and you've got yourself the format you need:
$DataContent |ConvertFrom-Csv -Delimiter "`t" |Export-Csv -Path $OUTCSV -NoTypeInformation

