Math expressions present a powerful tool to derive values from product data inputs. It is useful to derive arbitrary attributes like tax-included prices, tax, shipping, etc.
Some examples where Math expression can be used:
A custom field representing tax that equals to 21% of product price.
A "Shipping and included" price that equals product price added with a shipping fee for a marketplace that takes only shipping and tax included prices.
Math expressions are available in price and sale price attributes. It is also available in 'Number' typed custom fields as in following screenshot:
