A jeweler purchases silver for use in its bespoke products. The company uses $180$ grams of silver per week and buys silver for $$2\mathrm{.}6$ per gram from a supplier. The cost to hold $1$ gram of silver in inventory for $1$ year is $$0\mathrm{.}52.$ Each time the company orders silver from the supplier, the company must pay a $$12$ order processing charge$/$fee$.$ What is the optimal order quantity $($in grams$)?$