Aptitude “Problems on H.C.F and L.C.M” – Tips and Tricks to Solve in IBPS PO and Clerk Exams with examples.
Rahul Sir, a renowned aptitude trainer associated with OdTutor, has helped thousands of banking aspirants master quantitative aptitude concepts through logical methods and shortcut techniques. Among the most important topics in IBPS PO and Clerk examinations are Problems on H.C.F (Highest Common Factor) and L.C.M (Least Common Multiple). These concepts form the foundation of number systems and frequently appear in prelims and mains examinations. Many candidates find H.C.F and L.C.M questions easy in theory but struggle with speed and accuracy during exams. Rahul Sir emphasizes understanding the relationship between factors and multiples instead of memorizing formulas blindly. Once students understand divisibility rules, prime factorization, and shortcut methods, they can solve complex questions within seconds. In IBPS PO and Clerk exams, questions on H.C.F and L.C.M are often combined with word problems involving bells, events, workers, distribution, grouping, and repetitive cycles. A strong command of these concepts not only helps in direct questions but also improves performance in Number Series, Simplification, and Data Interpretation sections. This guide covers practical tips, tricks, formulas, and examples that Rahul Sir recommends for mastering H.C.F and L.C.M. By following these techniques consistently and practicing regularly, aspirants can significantly improve their speed and confidence while attempting banking aptitude questions. 1. Understanding the Basics of H.C.F and L.C.M Before learning shortcuts, students must clearly understand what H.C.F and L.C.M represent. H.C.F (Highest Common Factor):The greatest number that divides two or more numbers exactly. L.C.M (Least Common Multiple):The smallest number that is exactly divisible by two or more numbers. Example: Find H.C.F and L.C.M of 12 and 18. Factors of 12 = 1, 2, 3, 4, 6, 12 Factors of 18 = 1, 2, 3, 6, 9, 18 Common factors = 1, 2, 3, 6 Therefore: H.C.F = 6 Multiples of 12 = 12, 24, 36, 48, 60… Multiples of 18 = 18, 36, 54… Common multiple = 36 L.C.M = 36 Understanding this basic concept is crucial because many aspirants jump directly to formulas without grasping the logic behind factors and multiples. Once the concept is clear, solving advanced banking questions becomes significantly easier. Rahul Sir advises students to spend adequate time mastering these fundamentals before attempting shortcut techniques. Strong basics ensure fewer mistakes and faster calculations during competitive examinations. 2. Prime Factorization Method for Quick Solutions Prime factorization is one of the most reliable methods for solving H.C.F and L.C.M questions. Example: Find H.C.F and L.C.M of 24 and 36. Prime factors: 24 = 2 × 2 × 2 × 3 36 = 2 × 2 × 3 × 3 For H.C.F: Take common factors with smallest powers. H.C.F = 2² × 3 = 4 × 3 = 12 For L.C.M: Take all factors with highest powers. L.C.M = 2³ × 3² = 8 × 9 = 72 This method is highly accurate and works well even for large numbers. Banking examinations frequently include questions where prime factorization provides the fastest path to the solution. Students should memorize prime numbers up to at least 100 and practice factorizing numbers quickly. With sufficient practice, identifying prime factors becomes almost automatic. Rahul Sir often recommends writing prime factors vertically because it reduces confusion and calculation errors. This systematic approach ensures maximum accuracy under exam pressure. 3. Product Formula Trick One of the most important formulas in aptitude exams is: H.C.F × L.C.M = Product of the Numbers For two numbers: HCF × LCM = First Number × Second Number Example: Two numbers are 24 and 36. HCF = 12 LCM = ? LCM = (24 × 36)/12 = 864/12 = 72 This formula is frequently used in IBPS examinations. Example: H.C.F = 8 LC.M = 120 One number = 24 Find the other number. 8 × 120 = 24 × Other Number 960 = 24 × Other Number Other Number = 40 Questions based on this concept are very common because they test conceptual understanding rather than lengthy calculations. Rahul Sir advises students to immediately identify opportunities to use this formula, as it can save valuable exam time and eliminate unnecessary calculations. 4. Shortcut for Finding H.C.F Using Division Method The division method is extremely useful when dealing with large numbers. Example: Find H.C.F of 84 and 126. 126 ÷ 84 = 1 remainder 42 84 ÷ 42 = 2 remainder 0 Therefore, H.C.F = 42 This method is much faster than writing all factors. Example: Find H.C.F of 198 and 252. 252 ÷ 198 = remainder 54 198 ÷ 54 = remainder 36 54 ÷ 36 = remainder 18 36 ÷ 18 = 0 Therefore, H.C.F = 18 The division method is particularly useful in banking exams where speed matters. Students should practice this technique regularly because it can solve large-number questions within seconds. Rahul Sir recommends performing rough calculations mentally while using the division method to reduce dependence on written work and increase speed during examinations. 5. Solving Word Problems Based on L.C.M Many IBPS questions involve repetitive events. Example: Two bells ring every 12 minutes and 18 minutes. If they ring together now, after how many minutes will they ring together again? L.C.M of 12 and 18 12 = 2² × 3 18 = 2 × 3² L.C.M = 36 Answer = 36 minutes Such questions appear frequently in banking exams. Common applications include: The key is recognizing that whenever events repeat at different intervals and meet again, L.C.M is generally required. Rahul Sir teaches students to immediately identify keywords like “together again,” “simultaneously,” and “after how long” as indicators that L.C.M may be involved. 6. Distribution and Grouping Problems Using H.C.F H.C.F is commonly used when items must be distributed into maximum equal groups. Example: 96 chocolates and 144 candies are to be packed into identical packets. Find the maximum number of packets. H.C.F of 96 and 144: 96 = 2⁵ × 3 144 = 2⁴ × 3² H.C.F = 2⁴ × 3 = 48 Answer = 48 packets Each packet contains: 96/48 = 2 chocolates 144/48 = 3 candies Whenever questions ask









