Calculations not working

I am hoping someone can help me solve this issue with my calculations.  My Total field is not calculating.  I have ZERO knowledge of JavaScript.  I have developed a fillable form where the use will first select a quantity from a dropdown between 1-10 of an item.  If they select a quantity of an item they will then be required to select the Size and then the Length, both of these fields are drop downs.  Failure to select a Size or Length will result in a message telling them they must select this information.  Next, the item has a fixed price per item, and this is a text field..  Lastly, I need to calculate the Total amount that the person is spending based off the Quantity selected and the fixed Price.

Ex.  User selects a Quantity of 5 jackets.  They then put in the size as Small and length as Regular.  One jacket costs $149.50.  So the amount in the Total column will show $747.50.  If the user later changes the Quantity of jackets they want to a quantity of 3 the Total column will change to display $448.50.

Here's what I have done so far.  The quantity field is a dropdown box.  The Item field is a read only text field.  The Size field is a dropdown box with Custom Calculation event.target.required = (this.getField("Qty1").valueAsString!=this.getField("Qty1").defaultValue); .  The Length field is a dropdown box with Custom Calculationevent.target.required = (this.getField("Size1").valueAsString!=this.getField("Size1").defaultValue); .  The price field is a read only text with the amount for that item.  Lastly, the Total column has the formula Value Is: Product X, Price 1, Qty1.  I have tried to Set Field Calculation order with the Size first, Length second, and Total last.

Thank you for all help that can be provided!