Ten per cent, then adjust
How Do People Work Out a Tip in Their Head?
Nobody calculates a tip exactly — they find ten per cent and nudge it.
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Step 1 of 5
Ten per cent needs no arithmetic.
Move the decimal point one place left and you have it. £46 becomes £4.60 without a single calculation.
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Step 2 of 5
Everything else is built from that.
Five per cent is half of ten. Fifteen per cent is ten plus half of ten. Twenty per cent is ten doubled. No new sums.
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Step 3 of 5
Then you round to something friendly.
Nobody hands over £6.90. Rounding to £7 changes the tip by pennies and makes the total easy to check.
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Step 4 of 5
Rounding the bill first is faster still.
You are buying an easy sum for about thirty pence. It is usually worth it. Treat £46 as £50, take ten per cent, and you get £5. You have over-estimated by pennies and saved yourself the awkward numbers.
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Step 5 of 5
Which is why estimating is the real skill.
The tip does not need to be right — it needs to be close and quick. Being able to land within a few per cent is worth more than exactness.
Some countries build service into the price precisely to remove this sum from the end of a meal.
The short version
Tips are found by moving the decimal point one place, building other percentages from that, and rounding to something friendly.
Try it yourself
Work out 12.5% of £64 in your head: 10% is £6.40, a quarter of that is £1.60, so £8.