A number your eye reads first
Why Does Everything Cost £4.99?
You read prices from the left, and shops know it.
-
Step 1 of 5
We read numbers left to right.
The leftmost digit arrives first and sets the impression. By the time you reach the pennies, you have already filed the price away.
-
Step 2 of 5
Place value makes the left digit worth most.
That is not a trick of the eye — the leftmost digit really does carry the most value, so reading it first is normally sensible.
-
Step 3 of 5
Rounding down is the natural mistake.
Asked to remember £4.99 people usually store 'about four pounds', not 'about five'. It is off by a penny and wrong by a pound.
-
Step 4 of 5
It compounds across a basket.
Ten items at £4.99 feel like forty pounds and cost £49.90. The gap grows with every item you drop in.
-
Step 5 of 5
The cure is to round up as you shop.
Treat every price as the next whole pound. You will over-estimate slightly, which is exactly the right direction for a total to be wrong in.
Historically it also forced the till to open for change, which stopped staff pocketing the note.
The short version
Prices end in 99 because people read the leftmost digit first and round down, so £4.99 gets filed as four pounds.
Try it yourself
Add up a basket rounding every price up to the next pound. Compare your total with the till receipt.
Topics