What is 20% of 20?
The answer is 4.
Result Explanation
20% of 20 = 4. Because 20% is one fifth, you can also do 20 ÷ 5 = 4. If you mean 20% off 20, then 4 is the discount and the new total is 16 (use the discount calculator for the before/after).
If you’re comparing two values (not taking a slice of one number), use the percentage change calculator. For reverse problems like “20 is 20% of what?”, use the reverse percentage calculator.
Why Four Drops Out So Cleanly
Twenty factorises as 2 × 2 × 5. Taking twenty percent removes one factor of five from the “per hundred” story and pairs the remaining twos with the rate’s 0.2, leaving a single 4. When the base is not a multiple of five, the fifth shortcut still works but the result often carries tenths—contrast this page with bases like nineteen, where 20% = 3.8 unless you round for display.
Doubling from ten to twenty is linear: percentage-of scales with the base when the rate is fixed. That is why teaching sequences move from 20% of 10 to this page—the mechanics stay identical while the pounds on the table double.
Mental Maths Shortcuts for 20% of 20
Fastest: 20 ÷ 5 = 4 (the fifth).
- 10% of 20 = 2; double it for 20% = 4.
- Two tens: 20% of 10 = 2 per tenner → 2 + 2 = 4.
If you know 25% of 20 = 5, shave off 5% of 20 = 1 to reach 4 again—handy when your head anchors on quarters first.
Real-World Examples
Example 1: Twenty percent off a £20 tee
The markdown is £4 and the ticket price becomes £16 if nothing else stacks on top.
Example 2: Cash-stuffing envelope
Allocating twenty percent of a £20 weekly float to “repairs” sets aside £4, leaving £16 for other envelopes if you follow strict percentages.
Example 3: Small gig fee
A platform quoting 20% of a £20 micro-job payout takes £4; the creator sees £16 before bank fees, not the other way around, unless the contract defines gross differently.
Example 4: Sanity check against two hundred
20% of 200 is 40. Your 4 is exactly one tenth of that slice because 20 is one tenth of 200—a quick order-of-magnitude check when invoices jump a decimal place.
Common Mistakes
- Multiplying 20 × 20 and forgetting the divide-by-hundred, then staring at 400 as if it were a plausible portion.
- Dividing the percentage 20 by 20 and calling the answer 1% nonsense—twenty percent always means divide the base by five when you use the fifth trick.
- Reporting £16 when the exam question only asked for twenty percent of £20—sixteen is the price after a discount, not the discount amount.
- Confusing “20% of 20” with “20 is 20% of what?”—the latter needs 20 ÷ 0.2 = 100, a different setup entirely.
- Treating 0.2% of twenty as if it were 20%, which collapses the true slice toward zero.
Related Links
FAQ
What is 20% of 20?
20% of 20 is 4.
How do you calculate 20% of 20?
Multiply 20 by 0.2, or divide 20 by 5 because 20% is one fifth.
What is 20% off 20?
20% off 20 is a reduction of 4, leaving 16.