How to add attribute to product which is multiplied by amount of products?

Hi,

Is there a plugin or just a function in Woocommerce itself which would allow me to add attributes to products as numbers and then WC would count those numbers together and show the total number in cart page?

I am developing a balloon web store and I would need to set the amount of gas each balloon will consume.

For example Balloon 1 consumes 1.5 units of gas. The customer orders 100 of those balls. I need to show the customer on the cart page that the order requires 150 units of gas (100 * 1.5).

I will manually set the amount of gas units needed for each product and I need WC to count all of them together for the cart page.

Much like the weight attribute in products: you set one value to each product and the system calculates them together in the cart.

I tried adding an attribute with the value of 1.5 but if I change the number of products in the cart to 100 the attribute value stays at 1.5. I would need it to change to 150…

Thanks for any advice!