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LESSON 191 OF 671 · PROJECTS: EVERYDAY PROGRAMS

Shopping Cart V2 - Tax and Discount

Practice

Add a discount and sales tax to a single-item purchase using integer math.

You start with:

item := "Coffee Mug"
price := 12
quantity := 3
taxRate := 8
discount := 5
_ = item

Build:

Subtotal: $36
Discount: $5
Tax: $2
Total: $33

Rules:

  • subtotal := price * quantity.
  • afterDiscount := subtotal - discount (the discount is a flat amount taken off before tax).
  • tax = afterDiscount * taxRate / 100 (integer division, so the result is rounded down). The tax is charged on the discounted amount.
  • total := afterDiscount + tax.
  • Build four lines (Subtotal, Discount, Tax, Total) and join them with a newline "\n" into one string result, then print it with fmt.Println(result).

Compute the four numbers (subtotal, afterDiscount, tax, total) before formatting.

Use strconv.Itoa(...) to convert each number to text before concatenating it.

Go's int / int truncates, so afterDiscount * taxRate / 100 already rounds down. 

item := "Coffee Mug"
price := 12
quantity := 3
taxRate := 8
discount := 5
_ = item

subtotal := price * quantity
afterDiscount := subtotal - discount
tax := afterDiscount * taxRate / 100
total := afterDiscount + tax
line1 := "Subtotal: $" + strconv.Itoa(subtotal)
line2 := "Discount: $" + strconv.Itoa(discount)
line3 := "Tax: $" + strconv.Itoa(tax)
line4 := "Total: $" + strconv.Itoa(total)
result := line1 + "\n" + line2 + "\n" + line3 + "\n" + line4
fmt.Println(result)

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