Technical stuff Requirements are like water. They're easier to build on when they're frozen.

Let’s start with the initialization:

{assign var="iItemOne" value=1}
{assign var="iItemTwo" value=2}

Beware that the first code is working, while the second is not:

{* Working sample *}

{assign var="iSum" value=$iItemOne+$iItemTwo}
Result of adding {$iItemOne} and {$iItemTwo} is {$iSum}.

{* Not working sample *}

{assign var="iSum" value=$iItemOne + $iItemTwo}
Result of adding {$iItemOne} and {$iItemTwo} is {$iSum}.