Multiplying two variables in XSLT-1 - xslt

Question

I have tried for hours to multiply 2 varibales in XSLT1 but I can't seem to figure it out.
The result shows in excel as NaN
I have searched for a while but I'm having trouble with this, just started using XSLT
Variables:
Weight = 10
Length = 12
XSLT:
<xsl:variable name ="content"><xsl:value-of select="$length * $weight" /></xsl:variable>
EDIT:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:rvmon="rosenbergverft.com:3D/2017/WeightMTO" xmlns:pdms="rosenbergverft.com:3D/2010/Models">
<xsl:output method="text" omit-xml-declaration="yes" standalone="no" media-type="text/xls" />
<xsl:decimal-format name="euro" decimal-separator="," grouping-separator="." />
<xsl:template match="/">Building block;Discipline;Area;Sub. Area;Syst. no.;Weight Item no.;Piecemark no.;Weight Item Descr.;CompType;Type code;Rating or Scedule;Spec.;Dim. (");Material;Cost Code COR;Weight Phase Code;Mod. Phase Code;Weight Status % (allow.);Mod. Constr. Code;Mod. Handl. Code;No. off;Unit Length/ Area (m,m2, m3);Unit Weight (kg/m, m2, m3);Unit Weight MON(kg/m, m2, m3);Net Dry Weight (kg);Gross Dry Weight (kg);Content Weight (kg);Installed weight;CoG East;CoG North;CoG Elevation;Ref. doc., dwg., P&ID etc.;Remarks;Cost for instrument valves [NOK];install code;MON Lift Code;Paint Surface;Insulation Class;
<xsl:for-each select="/rvmon:WeightMTO/rvmon:MTOOwner"><xsl:for-each select="rvmon:Piecemark/rvmon:WeightItemNo/rvmon:Part">
<xsl:variable name= "weight" select="format-number(rvmon:ContentWeight/#number, '#0,0##', 'euro')" />
<xsl:variable name="length"><xsl:choose><xsl:when test="contains(rvmon:CompType,'BOLT')"><xsl:text> 1 </xsl:text></xsl:when><xsl:when test="rvmon:UnitLength/#unit = 'mm'"><xsl:value-of select="format-number(rvmon:UnitLength/#number div 1000, '#0,0##', 'euro')" /></xsl:when><xsl:when test="rvmon:UnitLength/#unit = 'mm2'"><xsl:value-of select="format-number(rvmon:UnitLength/#number div 1000000, '#0,0##', 'euro')" /></xsl:when><xsl:when test="rvmon:UnitLength/#unit = 'mm3'"><xsl:value-of select="format-number(rvmon:UnitLength/#number div 1000000000, '#0,0##', 'euro')" /></xsl:when><xsl:otherwise><xsl:value-of select="format-number(rvmon:UnitLength/#number, '#0,0##', 'euro')" /></xsl:otherwise></xsl:choose></xsl:variable>
<xsl:variable name="content" select="$length * $weight" />
<xsl:value-of select="../../../rvmon:BuildingBlock" />;<xsl:value-of select="rvmon:Discipline" />;<xsl:value-of select="../../../rvmon:Module" />;<xsl:value-of select="../../../rvmon:SubArea" />;<xsl:value-of select="../../../rvmon:SystNo" />;<xsl:value-of select="rvmon:WeightItemNo" />;<xsl:value-of select="rvmon:Piecemark" />;<xsl:value-of select="rvmon:WeightItemDescr" />;<xsl:value-of select="rvmon:CompType" />;<xsl:value-of select="rvmon:TypeCode" />;<xsl:value-of select="rvmon:Rating" />;<xsl:value-of select="rvmon:Spec" />;<xsl:choose><xsl:when test="rvmon:Discipline = 'L'"><xsl:value-of select="format-number(rvmon:Dim/#number, '#0,##', 'euro')" /><xsl:choose><xsl:when test="rvmon:Dim/#unit = 'inch'">"</xsl:when><xsl:otherwise><xsl:value-of select="rvmon:Dim/#unit" /></xsl:otherwise></xsl:choose></xsl:when><xsl:when test="rvmon:Discipline = 'N'"></xsl:when><xsl:otherwise><xsl:value-of select="format-number(rvmon:Dim/#number, '#0,##', 'euro')" /><xsl:value-of select="rvmon:Dim/#unit" /></xsl:otherwise></xsl:choose>;<xsl:value-of select="rvmon:Material" />;<xsl:value-of select="rvmon:CostCodeCOR" />;<xsl:value-of select="rvmon:WeightPhaseCode" />;<xsl:value-of select="rvmon:ModPhaseCode" />;<xsl:value-of select="format-number(rvmon:WeightStatus/#number * 100, '00', 'euro')" />%;<xsl:value-of select="rvmon:ModConstrCode" />;<xsl:value-of select="rvmon:ModHandlCode" />;<xsl:value-of select="format-number(rvmon:NoOff/#number, '#0,###', 'euro')" />;<xsl:value-of select="$length"/>;<xsl:if test="rvmon:ModHandlCode = 'RP'">-</xsl:if><xsl:value-of select="format-number(rvmon:UnitWeight/#number, '#0,0##', 'euro')" />;<xsl:if test="rvmon:ModHandlCode = 'RP'">-</xsl:if><xsl:value-of select="format-number(rvmon:MONUnitWeightFactor/#number, '#0,0#####', 'euro')" />;<xsl:choose><xsl:when test="contains(rvmon:CompType,'BOLT')"><xsl:text> 1 </xsl:text></xsl:when><xsl:otherwise><xsl:value-of select="format-number(rvmon:NetDryWeight/#number, '#0,0##', 'euro')" /></xsl:otherwise></xsl:choose>;<xsl:value-of select="format-number(rvmon:AllowanceWeight/#number, '#0,0##', 'euro')" />;<xsl:if test="rvmon:ModHandlCode = 'RP'">-</xsl:if><xsl:value-of select="$weight"/>;<xsl:if test="rvmon:ProdStatus ='ABC' "><xsl:text> Yes </xsl:text></xsl:if>;<xsl:value-of select="format-number(rvmon:CoGEast/#number div 1000, '#0,0##', 'euro')" />;<xsl:value-of select="format-number(rvmon:CoGNorth/#number div 1000, '#0,0##', 'euro')" />;<xsl:value-of select="format-number(rvmon:CoGElevation/#number div 1000, '#0,0##', 'euro')" />;<xsl:value-of select="../../../rvmon:DrawNumber" />;<!-- xsl:value-of select="rvmon:Remarks" / --><xsl:value-of select="../../../pdms:PDMSElement/pdms:ElementName/#text" />;;;;<xsl:value-of select="format-number(rvmon:PaintSurface/#number div 1000000, '#0,0##', 'euro')" />;<xsl:value-of select="../../../rvmon:InsulationClass" />;<xsl:value-of select="$length"/>;<xsl:value-of select="$content"/><xsl:text>
</xsl:text></xsl:for-each>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
XML-document
<UnitLength number="1.000" unit="pcs" field="Quantity" />
<ContentWeight number="8.005" unit="kg" field="ContentWeight" /> />
I am able to output "weight" and "length" by itself. But I cant even do
"weight * 10"
Sorry if it is messy.

Answer 1

You need to remove all formatting number while assigning the variable and while multipled result need to format number like below:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:rvmon="rosenbergverft.com:3D/2017/WeightMTO"
exclude-result-prefixes="#all"
version="1.0">
<xsl:decimal-format name="euro" decimal-separator="," grouping-separator="." />
<xsl:output method="html" indent="yes"/>
<xsl:template match="/">
<xsl:variable name= "weight" select="//rvmon:ContentWeight/#number" />
<xsl:variable name="length">
<xsl:choose>
<xsl:when test="contains(//rvmon:CompType,'BOLT')">
<xsl:text>1</xsl:text>
</xsl:when>
<xsl:when test="rvmon:UnitLength/#unit = 'mm'">
<xsl:value-of select="//rvmon:UnitLength/#number div 1000" />
</xsl:when>
<xsl:when test="rvmon:UnitLength/#unit = 'mm2'">
<xsl:value-of select="//rvmon:UnitLength/#number div 1000000" />
</xsl:when>
<xsl:when test="rvmon:UnitLength/#unit = 'mm3'">
<xsl:value-of select="//rvmon:UnitLength/#number div 1000000000" />
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="//rvmon:UnitLength/#number" />
</xsl:otherwise>
</xsl:choose>
</xsl:variable>
<xsl:variable name="content" select="format-number(($weight * $length), '#0,0##', 'euro')" />
<xsl:value-of select="$content"/>
</xsl:template>
</xsl:stylesheet>

Answer 2

You have:
<xsl:variable name= "weight" select="format-number(rvmon:ContentWeight/#number, '#0,0##', 'euro')" />
A number formatted to use a decimal comma is no longer a number for the purposes of XPath/XSLT. A number can contain only digits and a decimal period.
Assuming that the original values (not shown in your question) are true numbers, use them for the multiplication, and format them only for the output.