1. The problem is to understand the number 15. 2. The number 15 is a positive integer. 3. It can be expressed as a product of prime factors: $$15 = 3 \times 5$$. 4. It is an odd number and is located between 14 and 16 on the number line. 5. In algebra, 15 can be used as a constant or coefficient in equations. Final answer: 15