Mathematical Operations
About 6 min · General Intelligence and Reasoning · English
Time worked out from the lesson's 346 words at 150 words a minute, plus a minute for each question.
Mathematical Operations is a reasoning topic where questions test your ability to manipulate arithmetic rules and symbols. Unlike direct calculation problems in the Mathematics section, these questions ask you to change the rules — swapping operators, finding missing signs, or applying non-standard operations.
Key ideas
- BODMAS hierarchy: Brackets > Orders (powers/roots) > Division = Multiplication (left to right) > Addition = Subtraction (left to right). This order never changes even when symbols are substituted.
- Sign substitution: The question defines a new meaning for standard operators. Example: "If + means ×, then solve 5 + 3". You must translate 5 + 3 into 5 × 3 = 15 using the given mapping.
- Conditional operations: Sometimes a custom symbol (like ⊗ or #) is defined with a formula. Example: "a ⊗ b means 2a + 3b". You substitute values into the formula to compute.
- Missing operator problems: Given an equation with blanks where operators should be, find which combination of +, −, ×, ÷ makes the equation true. Test systematically using BODMAS.
- Equation balancing: Some questions ask "which two signs should be interchanged to make this equation correct?" You try swaps and verify using BODMAS.
Quick reference
- BODMAS never changes: Brackets > Orders > Division = Multiplication > Addition = Subtraction (apply after substitution).
- Two-step method: Translate using given rules first, calculate using BODMAS second.
- Common swap: + ↔ ×, − ↔ ÷.
- Custom symbols: Substitute values into the given formula exactly as defined.
- Missing operators: Test systematically; BODMAS eliminates wrong options fast.
Check yourself: 3 questions
1. If '+' means '÷', '÷' means '−', '−' means '×' and '×' means '+', then what is the value of 80 + 4 − 3 × 12 ÷ 6 ?
2. Select the missing operator from the options to make the equation correct: 144 ? 12 ? 2 = 24
3. If 'P' means '+', 'Q' means '−', 'R' means '×' and 'S' means '÷', then what is the value of: 15 P 9 S 3 Q 4 R 2 ?
This lesson is cut from the topic's note, not rewritten. Fact-checked on 18 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain. The questions are from Shishya's validated question bank.
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