Webinars SET A - Grade 5-6 - Sunday@4:30-5:30pm EST-Recording Webinar 5

Video Transcription

Video Summary

This webinar, targeted at Level 5-6 students, focuses on multiples, factors, and divisibility—key concepts frequently tested in math contests like Math Kangaroo and Olympiads. The session begins by exploring factors and how numbers multiply to form products, emphasizing that a factor divides evenly with no remainder. Using 2004 as an example, divisibility rules for numbers like 3, 4, 6, 8, and 12 are applied, demonstrating techniques such as examining digit sums or last digits.<br /><br />The presenter explains multiples as products of integers and discusses common multiples, providing strategies to identify them. Factor pairs are introduced as a method to organize factors systematically, with the example of 24. Prime numbers—divisible only by 1 and themselves—are explained, distinguishing them from composite numbers with multiple factors. Factor trees are demonstrated to find prime factorization, exemplified by the number 18 being broken down into 2 × 3 × 3.<br /><br />A divisibility table is reviewed, covering rules for divisibility by 2, 3, 4, 5, 6, 7, 8, 9, 10, and 100. Notable tips include layering divisibility rules and a unique rule for 7 involving digits manipulation. Several interactive poll problems test understanding—such as counting prime factors of 2000, determining numbers divisible by both 2 and 7, and logical deduction involving conflicting statements about a mystery number.<br /><br />The webinar also tackles practical problems: calculating the least common multiple (LCM) to find when multiple students all meet again, counting divisors of a product, and determining five-digit numbers meeting divisibility and digit uniqueness conditions. A key problem involves packing marbles into boxes evenly, solved using the greatest common factor (GCF).<br /><br />The session concludes by highlighting the importance of these concepts for problem-solving efficiency and fraction simplification. The instructor encourages practicing these foundational skills to succeed in contests and thanks students for participation, inviting them to review the webinar recording for deeper understanding.

Keywords

multiples

factors

divisibility

prime numbers

composite numbers

factor pairs

factor trees

prime factorization

least common multiple (LCM)

greatest common factor (GCF)