RRB Group D · Bite-size lessons

BODMAS

About 5 min · Mathematics · English

Time worked out from the lesson's 297 words at 150 words a minute, plus a minute for each question.

BODMAS (Brackets, Orders, Division, Multiplication, Addition, Subtraction) is the universal rule for the order in which mathematical operations must be performed when simplifying expressions.

Key ideas

• BODMAS hierarchy: Always perform operations in this strict order: Brackets first, then Orders (powers and roots), then Division and Multiplication (left to right), finally Addition and Subtraction (left to right). Never work purely left-to-right unless that happens to match BODMAS order.
• Division and Multiplication have equal priority: When both appear in an expression, perform them left to right as they occur. The same applies to Addition and Subtraction — equal priority, left-to-right execution. Many errors come from assuming multiplication always precedes division.
• Bracket types and priority: Simplify innermost brackets first. The hierarchy is: ( ) parentheses/round brackets first, then { } curly/braces, then [ ] square brackets. Always work inside-out when brackets are nested.
• "Of" means multiplication: In Indian exam context, "of" is a multiplication operator. For example, "1/2 of 40" means 1/2 × 40 = 20. This can appear in word problems disguised as BODMAS questions.
• Negative signs and brackets: Treat negative signs carefully. -3² means -(3²) = -9, but (-3)² means (-3)×(-3) = 9. The bracket placement changes the result entirely. Always clarify what the negative sign applies to.

Quick reference

• B-O-DM-AS hierarchy: Brackets → Orders → Division/Multiplication (L-R) → Addition/Subtraction (L-R)
• Division and Multiplication are equal priority (left to right), as are Addition and Subtraction
• "of" always means multiply (×)
• Nested brackets: always solve innermost first, then work outward
• Powers/roots come before all multiplication and division

Check yourself: 3 questions

This lesson is cut from the topic's note, not rewritten. Fact-checked on 21 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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