I am receiving invoices in HKD I do not need to keep track of the HKD total,
only the USD total. The invoices are for different amounts.

My goal is to enter the invoice total and have a formula in place that will
automatically convert the HKD amount to USD using an exchange rate of 7.8 by
dragging down the formula. I am trying to avoid having to type =HKD/7.8
Column B is for invoice total in USD (In my efforts to find a solution I
have designated cell B21 for the exchange rate which is 7.8)

Does anyone know if there is a simpler solution then typing =HKD/7.8?