SSC GD · Bite-size lessons

Fundamental Arithmetical Operations

About 6 min · Elementary Mathematics · English

Time worked out from the lesson's 367 words at 150 words a minute, plus a minute for each question.

Fundamental Arithmetical Operations form the backbone of the Elementary Mathematics section in SSC GD. Every question—whether it's percentage, profit-loss, or time-distance—ultimately relies on your speed and accuracy in basic arithmetic and simplification. This topic tests your ability to apply the correct order of operations (BODMAS/BODMAS rule), handle fractions and decimals, and simplify complex numerical expressions within strict time constraints.

Key ideas

• BODMAS Rule: The universal order of operations is Brackets first, then Orders (powers/roots), followed by Division and Multiplication (left to right), and finally Addition and Subtraction (left to right). Many students misremember this as "do multiplication before division"—both have equal priority and are solved left to right.
• Brackets Hierarchy: When multiple brackets appear, solve innermost first: ( ) are solved first, then { }, then [ ]. Always work inside-out, simplifying the deepest nested operation before moving outward.
• Left-to-Right Rule: For operations of equal priority (division and multiplication, or addition and subtraction), always proceed from left to right. The expression 20 ÷ 4 × 5 equals (20 ÷ 4) × 5 = 25, not 20 ÷ (4 × 5) = 1.
• Fraction Operations: To add/subtract fractions, find the LCM of denominators. To multiply, multiply numerators and denominators directly. To divide, multiply by the reciprocal of the divisor. Mixed fractions must be converted to improper fractions before any operation.
• Decimal Alignment: When adding or subtracting decimals, align decimal points vertically. When multiplying, count total decimal places in both numbers and place the point accordingly in the answer. For division, shift the decimal in divisor to make it whole, then shift equally in dividend.

Quick reference

• BODMAS order: Brackets → Orders → Div/Mult (L→R) → Add/Sub (L→R)
• Equal priority operations: Always solve left to right
• Fraction addition: Common denominator required; multiplication does not need it
• Negative × Negative = Positive; Negative × Positive = Negative
• Any number × 0 = 0; division by 0 is undefined

Check yourself: 3 questions

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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