Hi,

To add the total number of quantities in the invoice report, Try below code

<template id="inherit_report_invoice_document"
inherit_id="account.report_invoice_document">
<xpath expr="//tbody[hasclass('invoice_tbody')]"
               position="inside">

               <t t-set="quantity_set" t-value="0.0"/>

       </xpath>

<xpath expr="//td[@name='account_invoice_line_name']"

               position="after">

               <t t-set="quantity_set" t-value="quantity_set + line.quantity"/>

       </xpath>

        <xpath expr="//t[@t-foreach='lines']"

position="after">

               <div>Total Quantity : <t t-out="quantity_set"/></div>

</xpath>

</template>

Add the above code in your custom module, and the output be like

Hope it helps

With great difficulty as Odoo in their wisdom have removed functionality in relation to the use of Studio to make very simple changes to a VERY IMPORTANT DOCUMENT of a business INVOICES and quotes etc. Errordoo strikes again. Thanks Odoo great work. We currently have people paying us a tax free total amount as this unchangeable value is on our invoices. Geez when was 17 released Hmmm a long time ago.