Worked out below step by step, with a table of related values and a live calculator so you can change the numbers.
Answer
72
80 − 10% × 80
%
=
You pay
Step-by-step working
1. Find the discount: 10 ÷ 100 × 80 = 8.
2. Subtract it from the original value: 80 − 8.
3. You save 8 and pay 72.
Check it: 72 + 8 = 80, the original price.
Formula
sale price = value − (percent ÷ 100) × value
A discount is the percentage taken away, so the price you pay is the original value minus that amount.
How 10% off 80 is worked out
A discount has two separate values: the amount removed and the final price. First calculate 10% of 80, which is 8. Then subtract that discount from the original 80.
The final amount is 72. Showing both figures prevents a common mistake: reporting the discount itself when the question asks for the price after the discount.
Reasonableness and accuracy checks
A positive discount below 100% must produce a final amount lower than the original.
Add the discount amount, 8, back to the final amount; the total should return to 80.
For money, round only the displayed final answer to the currency precision required; keep full precision during the calculation.
Shortcut: calculate the percentage that remains
Instead of finding the discount and subtracting it, calculate the part that remains after the discount. A 10% discount leaves 90% of the original 80.
1.Remaining percentage = 100% − 10% = 90%.
2.Convert 90% to 0.9.
3.80 × 0.9 = 72.
A second worked example
What is 10% off 160?
160 − 10% × 160 = 144
Find the discount: 10 ÷ 100 × 160 = 16. Subtract it from the original value: 160 − 16. You save 16 and pay 144. This uses the same method with different numbers, so it shows how the rule transfers instead of only repeating the original answer.
What the discount numbers tell you
A 10% discount removes 8 from 80 and leaves 90% of the original amount. The retained-value multiplier is 0.9, which leads to the final value 72.
Where discount calculations are useful
This method applies to sale prices, negotiated reductions, coupon discounts and budget savings. Keeping the discount amount and the final amount separate helps when checking receipts, comparing offers or explaining a price reduction.
Common mistakes to avoid
Reporting the discount amount as the final price instead of subtracting the discount from the original amount.
Forgetting that 10% off leaves 90% of the original value.
Rounding the discount before the final subtraction when currency rules require greater intermediate precision.
Questions about this calculation
Is there another way to check What is 10% off 80?
Instead of finding the discount and subtracting it, calculate the part that remains after the discount. A 10% discount leaves 90% of the original 80. Remaining percentage = 100% − 10% = 90%. Convert 90% to 0.9. 80 × 0.9 = 72.
What is the most common mistake with What is 10% off 80?
Reporting the discount amount as the final price instead of subtracting the discount from the original amount. After correcting that setup, verify the result independently: Check it: 72 + 8 = 80, the original price.
Can I use the same method with different numbers?
Yes. What is 10% off 160? Find the discount: 10 ÷ 100 × 160 = 16. Subtract it from the original value: 160 − 16. You save 16 and pay 144. This uses the same method with different numbers, so it shows how the rule transfers instead of only repeating the original answer. The live calculator above lets you replace both inputs and recalculate without changing the underlying method.
How can I tell whether 72 is reasonable here?
A 10% discount removes 8 from 80 and leaves 90% of the original amount. The retained-value multiplier is 0.9, which leads to the final value 72. Use that scale or ratio check together with the reverse calculation before reusing the result in another calculation.