# 5: Basic Number Theory

- Page ID
- 8413

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- 5.2: Division Algorithm
- When we divide a positive integer (the dividend) by another positive integer (the divisor), we obtain a quotient. We multiply the quotient to the divisor, and subtract the product from the dividend to obtain the remainder. Such a division produces two results: a quotient and a remainder.

- 5.3: Divisibility
- In this section, we shall study the concept of divisibility.

- 5.6: Fundamental Theorem of Arithmetic
- Primes are positive integers that do not have any proper divisor except 1. Primes can be regarded as the building blocks of all integers with respect to multiplication.

*Thumbnail: Golden spiral. Assuming a square has the side length of 1, the next smaller square is 1/φ wide. Then a width of 1/φ², 1/φ³ and so on. Image used with permission (Public Domain; Jahobr).*