IQ Test: What Number Is Missing? How to Solve Them
To solve an IQ test "what number is missing" puzzle, check the numbers in a fixed order: rows, then columns, then diagonals or opposite pairs, then the basic operations, then two-step combinations. Nearly every missing number puzzle, from school worksheets to viral posts, uses one of those five. Running them in order turns staring and guessing into a method.
If number puzzles make you freeze, or the arithmetic keeps slipping while you juggle the rule, IQ Tester spots which one it is and trains it daily. Find my weak spots
The five-check method
Here's the whole method on one card. Keep it in mind as you read the examples.
| Check | Ask yourself | Example rule |
|---|---|---|
| 1. Rows | Does each row follow a rule? | first × second = third |
| 2. Columns | Does each column follow a rule? | top + middle = bottom |
| 3. Diagonals or opposites | Do diagonals, or numbers across a circle, pair up? | opposite numbers add to 20 |
| 4. Single operations | Is it +, −, × or ÷? | center = product of corners |
| 5. Two-step combos | Is it two operations joined? | a × b − a |
Work down the list. The moment a rule fits every complete row, column or group, you've got it. If it fits only some, keep going.
Before you start
- Look at the size of the numbers. Big jumps suggest multiplying. Small, steady changes suggest adding.
- Find the complete groups. The rule has to work on all of them before you trust it on the one with the gap.
- Say the rule in a sentence before you calculate the answer.
Row and column rules
Most iq test find the missing number puzzles in grid form use rows or columns. Start there.
Example 1: a row rule
3 4 12
5 2 10
6 ? 42
Check rows. 3 × 4 = 12. 5 × 2 = 10. It holds for both full rows, so the rule is "first times second equals third."
Answer: 7, since 6 × 7 = 42.
Example 2: a column rule
8 3 5
6 2 4
14 5 ?
Check rows first. 8, 3, 5 and 6, 2, 4 don't share an obvious rule. Check columns. 8 + 6 = 14. 3 + 2 = 5. Holds for both full columns.
Answer: 9, since 5 + 4 = 9.
This is why the order matters. If you only ever check rows, column puzzles look impossible.
Circle and triangle puzzles
Viral missing number puzzles love circles and triangles. The layout is different, but the checks are the same.
Example 3: a circle
Six numbers sit around a circle, split into three pairs of opposites: 3 and 17, 8 and 12, 5 and ?
Check opposites. 3 + 17 = 20. 8 + 12 = 20. Opposite numbers add up to 20.
Answer: 15.
Circle puzzles often use opposites, neighbors, or a number in the middle made from the ones around it. Try each in turn.
Example 4: triangles
Three triangles, each with a number at every corner and one in the middle:
- Corners 2, 3, 4, middle 24
- Corners 1, 5, 6, middle 30
- Corners 2, 2, 7, middle ?
Check operations. Adding the corners gives 9 and 12, not 24 and 30. Multiplying gives 2 × 3 × 4 = 24 and 1 × 5 × 6 = 30. Match.
Answer: 28, since 2 × 2 × 7 = 28.
When the rule uses two operations
The harder iq test number questions combine two operations. These feel impossible if you only try one step at a time.
Example 5: multiply, then subtract
4 5 16
3 6 15
7 2 ?
Single operations first. 4 × 5 = 20, not 16. 4 + 5 = 9, not 16. Nothing simple fits.
Two-step check. The results are a bit less than the product (20 → 16, 18 → 15). How much less? 4 and 3, which are the first numbers in each row. So the rule is "first times second, minus first."
- 4 × 5 − 4 = 16 ✓
- 3 × 6 − 3 = 15 ✓
- 7 × 2 − 7 = 7
Answer: 7.
A tip for two-step puzzles
Compare the answer to the nearest simple result. Ask: "How far off is it, and is that difference one of the numbers I can see?" That question cracks most combo rules.
This is the moment a lot of people get stuck. You're holding the grid, a guessed rule and three calculations in your head at once, and one slip wrecks it. Knowing whether the trouble is the arithmetic, the holding, or spotting the rule is hard to judge yourself. IQ Tester's 16 questions tell apart mental arithmetic, working memory and pattern spotting, then give you a daily 10-minute drill, like "Estimate first," aimed at the one that's really tripping you. Find my weak spots
Worked examples: mixed practice
Try these three before reading the answers. Run the five checks in order.
Puzzle A
2 9 11
7 4 11
5 ? 11
Puzzle B
Circle with opposite pairs: 6 and 36, 3 and 9, 5 and ?
Puzzle C
12 3 4
20 5 4
18 ? 6
Answers:
- A: 6. Each row adds to 11 (check 1, rows).
- B: 25. Each outer number is the square of its opposite: 6² = 36, 3² = 9, 5² = 25 (check 3, opposites).
- C: 3. First ÷ second = third: 12 ÷ 3 = 4, 20 ÷ 5 = 4, 18 ÷ 3 = 6 (check 4, operations).
For more number puzzles that follow a sequence instead of a grid, see 3, 5, 9, 17 and 2, 6, 12, 20, 30. And if you want tougher items with the same step-by-step reasoning, try hard IQ test questions with answers explained.
Making your own
Building a missing number puzzle is one of the best ways to get good at solving them. You start thinking like the person who wrote it.
- Pick a rule. Keep it simple first: "row adds to 15" or "first times second."
- Build three complete rows that follow it.
- Hide one number.
- Check there's only one answer. If two rules fit the full rows, change a number so only yours works.
- Swap with a friend. Time each other, then explain your rules.
Once one-step puzzles feel easy, try two-step rules, circles with opposites, or triangles with a center number. You'll start recognizing these the moment a viral post shows up in your feed.
Crack the missing number every time
The five checks (rows, columns, diagonals, operations, combos) handle almost any iq test what number is missing puzzle. IQ Tester's 16-question check takes about two minutes and shows whether mental arithmetic, working memory or pattern spotting is the part that slows you down. From there you get one tip and one roughly 10-minute drill a day, weighted toward your weak spots, and you can retest whenever you want.
FAQ
How do you solve find the missing number puzzles?
Check rows, then columns, then diagonals or opposite pairs, then single operations, then two-step combinations. The right rule fits every complete group, not just one.
What is the trick to missing number puzzles?
There isn't one trick, but there is a reliable order of checks. Most puzzles use rows, columns or opposites combined with basic arithmetic. Checking in order stops you from guessing.
Why are missing number puzzles on IQ tests?
They measure pattern spotting and number reasoning together. You have to find a hidden rule and apply it accurately, which is a core part of reasoning.
How do you solve a missing number in a circle puzzle?
Look at opposite pairs first, then neighbors, then whether a center number comes from the outer ones. Test each rule on all complete pairs before trusting it.
Are viral missing number puzzles hard?
Most use one simple rule hidden in an unusual layout. The layout makes them look harder than they are. The five-check method solves the large majority of them.