Do calculation in mini lang
<!-- A = B * C -->
<calculate field="A" type="BigDecimal">
<calcop field="B" operator="multiply">
<calcop field="C" operator="get"/>
</calcop>
</calculate>
<!-- A = A / 100 -->
<calculate field="A" type="BigDecimal">
<calcop field="A" operator="divide">
<number value="100"/>
</calcop>
</calculate>