Since its inception in 2009, the value of Bitcoin has fluctuated significantly, making it challenging to determine the current value of a certain amount of Bitcoin purchased on a particular date in the past. 

This Bitcoin Value Calculator takes the amount of Bitcoin purchased and the date of purchase as inputs and gives the current value of the Bitcoin as the output. It uses the historical price data of Bitcoin to determine the present value of the cryptocurrency. 

To use the Bitcoin Value Calculator, input the date and amount of Bitcoin purchased. The calculator would then search for the historical data of Bitcoin prices on that particular day and calculate the current value of the Bitcoin using the current market price.