Error checking tests give you original records and copies, and ask how many copies are wrong, or where. The errors are small on purpose, and they fall into a few families:
- Transposed digits: 40817 copied as 40871.
- Look-alike characters: the letter O for zero, a lowercase l for the number 1, S for 5, B for 8.
- Dropped letters in names: Lindqvist copied as Lindqvst.
- Swapped day and month: 2026-03-07 copied as 2026-07-03.
Check one column at a time down the page, not one row across. Your eyes settle into a single kind of comparison, and you catch more. Read numbers in chunks of two or three digits, and read names letter by letter, not as words: the brain fills in a familiar name and skips the missing letter. Some rows have no errors at all; count them as correct rather than hunting for a change that isn't there.