Concept 6 of 8Foundation
Watch on YouTubeVideoLCM (Least Common Multiple)
LCM = smallest number that is a multiple of ALL given numbers.
With prime factorization: take each prime at its HIGHEST power across the numbers.
LCM of 12 and 18:
12 = 2² × 3, 18 = 2 × 3². LCM = 2² × 3² = 36.
Magic formula: HCF × LCM = a × b. (6 × 36 = 216 = 12 × 18 ✓)
Example
LCM of 4 and 6 = 12 (smallest number both divide).
Buses A every 12 min, B every 18 min. Both together at 10:00 — next together at 10:36 (LCM).
Buses A every 12 min, B every 18 min. Both together at 10:00 — next together at 10:36 (LCM).
💡 Tip:LCM solves 'when do they meet again / smallest common thing' problems.
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5 questions to check what you just read.
0 / 5
- Q1.LCM of 4 and 6:
- Q2.LCM of 9 and 15:
- Q3.LCM of two co-primes 7 and 8:
- Q4.LCM of 10 and 25:
- Q5.LCM × HCF of 12 and 18 equals: