Calculating GST

To calculate how much GST to add: Multiply by 0.1

decGST = decSubTotal  *  0.1

To add GST to arrive at a total price: Multiply by 1.1

decTotalPrice = decSubTotal * 1.1

To calculate how much GST is included in a price: Divide by 11

decGST = decTotalPrice / 11

To calculate how much the price was before GST: Divide by 1.1

decSubTotal = decSubTotal / 1.1


From "Calculate GST in the Blink of an Eye - For Dummies" ( http://bit.ly/efOjUP )