Number sequences are one of the most common question types in the TR-YÖS numerical ability test. They look like puzzles, but nearly all of them use a small set of rules. Try the rules in a fixed order and test each one against every term. The examples below are EXAMEV practice questions, not ÖSYM questions.
The order to try
- 1Differences between neighbours: constant, growing by a fixed amount, or themselves a pattern.
- 2Ratios: multiply or divide by the same number.
- 3Two sequences mixed together: odd positions and even positions follow different rules.
- 4Combinations: ×2 then +1, squares, primes.
Example 1: 3, 7, 11, ?, 19
Differences: 4, 4. Rule: add 4. The missing term is 11 + 4 = 15, and 15 + 4 = 19 confirms it.
Example 2: 1, 2, 4, 7, 11, ?
Tempting rule: double each term (1, 2, 4, 8...). It fails at the fourth term, which is 7, not 8. Differences: 1, 2, 3, 4, so each difference grows by 1. Next difference 5, so the answer is 11 + 5 = 16.
Example 3: 5, 20, 7, 18, 9, 16, ?
Neighbour differences jump around (+15, −13, +11...), a sign of two mixed sequences. Odd positions: 5, 7, 9 (add 2). Even positions: 20, 18, 16 (subtract 2). The missing term is in position 7, an odd position, so it is 9 + 2 = 11.
A pattern must fit all the given terms, not just the first pair. Test your rule on every term before you choose an answer.
Speed
TR-YÖS has 80 questions in 100 minutes, so a sequence question deserves about a minute. If no rule appears after the four checks above, mark it and come back later.
How EXAMEV helps
The EXAMEV TR-YÖS Numerical Aptitude and Basic Mathematics bank has over 1,300 practice questions, including more than 100 on number sequences and finding rules, with explanations and timed sessions. For the full exam and a six-week plan, read our TR-YÖS preparation guide.