Logical Reasoning: Missing Numbers

Concept Explanation

Missing number items (IndiaBIX / Infosys-style LR) show a grid, triangle, cross, or magic square with one blank. Unlike plain number series, the rule ties to position: row sum, column product, opposite corners, or parent = sum of children.

Patterns you will see

• Magic square: every row, column and diagonal has the same sum (often 15 for 3×3).
• Triangle / pyramid: each upper cell equals the sum of the two cells below it.
• Cross / diamond: vertical sum equals horizontal sum through the centre.
• Matrix rules: middle = average of neighbours; last = first × second; third = second − first.
• Embedded mini-series: one row listed as 1, 4, 9, 16, ? (squares).

How to solve fast

1. State the rule in one line (e.g. “each row sums to 20”) before calculating.
2. Check rows first, then columns; diagonals last for magic squares.
3. Do not import a series formula from another row unless the grid shows the same rule twice.