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How to solve domino sequence puzzles

Dominoes: two lanes on a seven-hour clock

A domino series is two independent number series — top lane and bottom lane — each counting 0–6 and wrapping like a clock.

Updated 30 September 2026

A row of dominoes with a blank final tile looks like one object evolving. It is usually two: the top halves form one sequence, the bottom halves another, each with its own rule — a constant step or an alternating pair of steps. Domino faces run 0 to 6 — after 6 the count wraps to 0, exactly like hours on a clock face. On the hardest items the two lanes are secretly COUPLED: the bottom is set so that top + bottom stays constant.

Read the lanes separately

Cover the bottom lane with a finger and read the top as a plain series: +1, +2, alternating, repeating a short block. Then cover the top and read the bottom. Each lane has its own simple rule; the puzzle's difficulty is only that both run at once.

The wrap is the trick

5, 6, 0, 1 is a +1 lane that wrapped. When a lane 'breaks its rule', add 7 mentally and re-check: 6 → 0 is +1; 5 → 2 is +4 (or −3, same thing mod 7). Wraps are where distractor options are farmed — an option one off from yours usually missed a wrap.

When the bottom lane looks lawless, add the halves

On the hardest items the bottom lane obeys no step rule of its own — because it is chained to the top. Add top and bottom on each tile: if the sum is the same everywhere (allowing the wrap past 7), you have found the rule. The top advances by its own step, and the bottom is whatever makes the sum come out constant.

The strategy

Top lane alone: state its step rule (constant or alternating), wrapping past 6.
Bottom lane alone: state its rule — and if none fits, add top + bottom on every tile and test for a constant sum.
Apply each rule once more to get the blank tile's two numbers.
Check the pair against the options — both halves must match, in position.

Common traps

Reading each domino as one two-digit number — read the lanes separately first.
Missing the 6→0 wrap and abandoning a correct rule.
Options with your two numbers swapped top-for-bottom — position matters.
Declaring the bottom lane 'random' and guessing — a lawless-looking lane is the signal to test the constant-sum rule.

Speed · ~40s/item: Two simple series read one at a time: 30–45 seconds. Wrap-checking is the only slow step worth the care.

Worked example

Made by the same generator and answer checker as the practice questions, at middling difficulty, but never served in a test. Commit to an option before you reveal — the pick is yours alone and is never recorded.

Which domino continues the series?

Reveal the answer

The answer is B.

Show why — the worked reasoning

Read the two halves as separate series — dominoes wrap after six (6 → 0, like a 7-hour clock). Here the top half advances +1 per tile and the bottom +2, each wrapping 6 → 0. Applying each half's rule once more gives 0 over 1. Traps: the swapped-halves option and off-by-one wraparound slips — always check the wrap.

Try it yourself: 4 practice questions

Pick an answer, then reveal it. Nothing is recorded, there is no clock, and none of these questions is ever used in a test.

Question 1 · Easy

Which domino continues the series?

Reveal the answer

The answer is B.

Show why — the worked reasoning

Read the two halves as separate series — dominoes wrap after six (6 → 0, like a 7-hour clock). Here the top half advances +3 per tile and the bottom +2, each wrapping 6 → 0. Applying each half's rule once more gives 1 over 5. Traps: the swapped-halves option and off-by-one wraparound slips — always check the wrap.

Question 2 · Easy

Which domino continues the series?

Reveal the answer

The answer is E.

Show why — the worked reasoning

Read the two halves as separate series — dominoes wrap after six (6 → 0, like a 7-hour clock). Here the top half advances +3 per tile and the bottom +2, each wrapping 6 → 0. Applying each half's rule once more gives 5 over 2. Traps: the swapped-halves option and off-by-one wraparound slips — always check the wrap.

Question 3 · Easy

Which domino continues the series?

Reveal the answer

The answer is B.

Show why — the worked reasoning

Read the two halves as separate series — dominoes wrap after six (6 → 0, like a 7-hour clock). Here the top half advances +3 per tile and the bottom +2, each wrapping 6 → 0. Applying each half's rule once more gives 2 over 6. Traps: the swapped-halves option and off-by-one wraparound slips — always check the wrap.

Question 4 · Easy

Which domino continues the series?

Reveal the answer

The answer is E.

Show why — the worked reasoning

Read the two halves as separate series — dominoes wrap after six (6 → 0, like a 7-hour clock). Here the top half advances +3 per tile and the bottom +1, each wrapping 6 → 0. Applying each half's rule once more gives 3 over 5. Traps: the swapped-halves option and off-by-one wraparound slips — always check the wrap.

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