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Series Completion MCQs

Series Completion MCQs are multiple-choice questions that ask you to find the next or missing term in a number series, letter series, alphanumeric series or repeating letter pattern. Every question on MCQs360 shows its correct answer instantly, so you can confirm the rule behind each series and build speed in spotting patterns.

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About Series Completion MCQs

Number series questions use rules such as constant or growing differences, multiplication followed by addition, squares and cubes of consecutive numbers or primes, and two series running alternately. Letter series use fixed jumps in alphabet position, such as moving forward five letters each time, and often wrap round from Z back to A. Mixed series pair letters with numbers, each following its own rule.

Repeating pattern questions give a string with blanks, such as a group of letters repeated with small changes, and ask which option fills the gaps in order. Series questions appear in almost every aptitude test, including MDCAT, NTS, SSC CGL and IBPS, and are usually quick marks once the common rules are familiar. Regular practice trains you to test the likely rules in a fixed order.

Key facts to remember

  • Letter positions run from A = 1 to Z = 26; a forward jump past Z continues from A (for example, Z + 5 = E).
  • The letters at positions 5, 10, 15, 20 and 25 are E, J, O, T and Y.
  • The squares of 11 to 25 (121 to 625) and cubes of 1 to 15 appear often in number series.
  • A series in which each term is double the previous term plus one (6, 13, 27, 55, ...) follows the rule ×2 + 1.
  • If the differences between terms are not constant, check the differences of the differences, or test alternate terms as two separate series.

Exams that include Series Completion MCQs

Pakistan

  • MDCAT
  • NTS
  • GAT
  • ISSB
  • Army, Navy and PAF initial tests
  • PPSC
  • FPSC

India

  • SSC CGL
  • SSC CHSL
  • IBPS PO
  • IBPS Clerk
  • SBI PO
  • SBI Clerk
  • RRB NTPC
  • CAT

Bangladesh

  • BCS
  • Bangladesh Bank recruitment tests

How to prepare for Series Completion MCQs

  1. Start by writing the differences between terms; if they do not reveal the rule, try ratios, squares, cubes and alternate terms.
  2. Convert letters to numbers using A = 1 to Z = 26 to see the jump clearly.
  3. In repeating letter patterns, split the string into equal groups of the likely repeat length before filling the blanks.
  4. Memorise squares up to 30 and cubes up to 15 so you recognise them instantly.

Frequently asked questions

How do I solve number series questions quickly?

Look at the differences first, then ratios. If neither works, check whether terms are squares, cubes or primes, or whether two series alternate. Most series in exams follow one of these rules, so checking them in a fixed order saves time.

Which exams ask Series Completion MCQs?

Series questions appear in MDCAT, NTS and GAT tests, ISSB and forces initial tests in Pakistan, SSC CGL, SSC CHSL, IBPS, SBI and RRB exams in India, and the BCS mental ability paper and bank tests in Bangladesh.

What do I do when a letter series passes Z?

The alphabet wraps round, so after Z you continue from A. For example, moving five letters forward from Z gives E. Subtracting 26 from a position above 26 gives the correct letter.

Last reviewed October 2026