Math 2.0

statement proposition

Existence of a prime divisor

Statement

Let nn be a natural number with n≥2n \ge 2. Then there is a prime number pp such that p∣np \mid n.

Remarks

One proof takes the smallest divisor dd of nn with d>1d > 1. Each divisor ee of dd with e>1e > 1 also divides nn, so e=de = d. Thus dd is prime. This smallest divisor is the smallest prime factor of nn. The result is also true for n=0n = 0, since each prime divides 00. It is false for n=1n = 1.

Explanations

L1 human

Split nn into two smaller factors when you can, and repeat with one of the factors. The numbers get smaller each time, so the process stops at a number that you cannot split. This number is a prime, and it divides nn. For example, 60=2⋅3060 = 2 \cdot 30, so 22 is a prime divisor of 6060.

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  1. Divisibility definition
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Sources

  1. Web https://en.wikipedia.org/wiki/Prime_number, Unique factorization