Number Theory Number Theory 1. Prime Numbers In this video, Teacher Jon introduces secondary students to the primes, making use of the sieve of Eratosthenes, and looks 2. Fibonacci Numbers In this video, Teacher Jon introduces the Fibonacci sequence using the question posed by Fibonacci in 1202, and continues with 3. Indices - an Introduction Indices : the First 4 Laws (Indices, Powers or Exponents) Introduces students to the first 4 laws of indices with 4. Indices - Word Problems Indices - Word Problems (Indices, Powers or Exponents) Solving simple word problems by looking for patterns using indices (or exponents 5. Factors and Multiples - The HCF and the LCM In this lesson, Teacher Jon explains Factors and Multiples, as well as the Highest Common Factors and Lowest Common Multiples.