Use Cases

Example 1. Calculate VAT on a product price

Scenario: You are a freelancer in the UK. A client agrees to pay you £500.00 including VAT. You need to know your earnings before VAT and the VAT amount.

Steps:

1. Tap the After field to make it active.
2. Set the rate to 20%
3. Enter 500.
4. The calculator shows:
   • Before: £416.67
   • Amount: £83.33

Example 2. Find the price including tax (Before → After)

Scenario: You are pricing a product at $120.00 before tax. You need to know the final shelf price including 8% sales tax.

Steps:

1. Open the quick rate popup (tap the rate badge on the toolbar).
2. Set the rate to 8%.
3. Tap the Before field to make it active.
4. Enter 120.
5. The calculator shows:
   • After: $129.60
   • Amount: $9.60

Example 3. Determine the original price from a tax amount

Scenario: You have an invoice showing a VAT amount of €45.00. The VAT rate is 21%. What was the original price?

Steps:

1. Open the quick rate popup and set the rate to 21%.
2. Tap the Amount field to make it active.
3. Enter 45.
4. The calculator shows:
   • After: €259.29
   • Before: €214.29

Example 4. Calculate commission on a sale

Scenario: You earn a 10% commission on every sale. You just closed a deal worth $5,000.00 (total sale amount). What is your commission?

Steps:

1. Set the rate to 10% (via the quick popup or Settings).
2. Tap the After field.
3. Enter 5000.
4. The calculator shows:
   • Before: $4,545.45 (the sale amount minus commission)
   • Amount: $454.55 (your commission)

Note: For commission, think of “After” as the total sale and “Amount” as the commission. The “Before” is what remains after commission.

Example 5. Add a tip to a restaurant bill

Scenario: Your restaurant bill is $85.00 (before tip). You want to add a 15% tip.

1. Set the rate to 15% (via the quick popup or Settings).
2. Tap the Before field.
3. Enter 85.
4. The calculator shows:
   • Before: $85.00 (your bill was $85.00)
   • After: $97.75 (you paid a total of $97.75 including tip)
   • Amount: $12.75 (the tip was $12.75)

Example 6. Calculate Zakat (2.5%) - subtractive mode

Scenario: You want to calculate your Zakat contribution at 2.5% of your qualifying wealth of $40,000.00. After paying Zakat, how much wealth remains?

Steps (using subtractive mode):

1. Set the rate to 2.5% (via the quick popup or Settings).
2. Tap the + button on the nudge toolbar to switch to − (subtractive mode). The toolbar now reads − 2.5%.
3. Tap the Before field (it will show “Before 2.5%” in the label).
4. Enter 40000.
5. The calculator shows:
   • Before (wealth before Zakat): $40,000.00
   • After (wealth after paying Zakat): $39,000.00
   • 2.5% Amount (your Zakat contribution): $1,000.00

Example 7. Apply a discount

Scenario: A store is offering 20% off all items. An item is priced at $80.00. What is the discounted price?

Steps (using subtractive mode):

1. Set the rate to 20% (via the quick popup or Settings).
2. Tap the + button on the toolbar to switch to − (subtractive).
3. Tap the Before field.
4. Enter 80.
5. The calculator shows:
   • Before (original price): $80.00
   • After (sale price): $64.00
   • 20% Amount (discount): $16.00

The subtractive mode approach is more intuitive for discounts: you enter the original price, and the calculator subtracts the percentage automatically.

Example 8. Net salary after deductions — subtractive mode

Scenario: Your gross salary is $6,000.00 per month. 7.5% is deducted for pension and insurance. What is your take-home pay?

Steps:

1. Set the rate to 7.5%.
2. Tap + → − to switch to subtractive mode.
3. Tap the Before field.
4. Enter 6000.
5. The calculator shows:
   • Before (gross salary): $6,000.00
   • After (take-home pay): $5,550.00
   • 7.5% Amount (deductions): $450.00

Summary

For any use case, the core workflow is the same:

set the rate → set the direction → choose your anchor → enter the value you know → read the other two.