Free ACT Error Detection practice
Error detection is the letter-checking section. You are shown four pairs of letters, one above the other, and you count how many pairs are the same letter. Case does not matter, so A and a match. It is pure attention to detail at speed, and the usual mistake is rushing past a look-alike pair such as b and d.
Read the full error detection guide →
Try a free sample
How many of the letter pairs are the same letter? (Upper and lower case count as the same letter.)
Tap an answer to move straight on — just like the real ACT. There is no going back.
Unlock all 5 ACT sections
One payment unlocks every section of the Army Cognitive Test — deductive reasoning, error detection, number fluency, word rules, orientation — with full question banks and unlimited mock tests. One-time payment, no subscription.
These are original practice questions written to reflect the publicly described format of the Army Cognitive Test (ACT). They are not the official questions and this site is not affiliated with or endorsed by the British Army or the Ministry of Defence — always follow the official guidance from your Armed Forces Careers Office.