Math Problem Statement

If a number can be represented by an all-purple train, an all-black train, and an all-blue train, it has at least eight factors. Name these factors in increasing order.

Solution

For a number to be represented by an all-purple train, an all-black train, and an all-blue train, it suggests that the number has enough divisors to form at least three different products that yield the same number. If a number has at least eight factors, these factors include 1, the number itself, and at least six other divisors.

Let's assume nn is our number, and it must be divisible in such a way that it has exactly or more than eight divisors. Numbers with eight divisors typically follow one of these structures:

  1. n=p7n = p^7, where pp is a prime (1 prime factor with exponent 7).
  2. n=p3×qn = p^3 \times q, where pp and qq are primes (1 prime with exponent 3 and another with exponent 1).
  3. n=p×q×rn = p \times q \times r, where pp, qq, and rr are distinct primes (each prime with exponent 1).

Each of these configurations will yield at least eight divisors for nn.

Example Solution

To satisfy the conditions, let's choose the simplest structure of three distinct primes, say 22, 33, and 55.

So, let n=2×3×5=30n = 2 \times 3 \times 5 = 30.

The factors of 30 are: 1,2,3,5,6,10,15,301, 2, 3, 5, 6, 10, 15, 30

These factors are in increasing order: 1, 2, 3, 5, 6, 10, 15, 30.

Thus, a number represented by an all-purple, all-black, and all-blue train could be 30, as it has exactly eight factors.

Would you like further explanation on divisor structures or more examples?


  1. What other numbers with eight divisors could satisfy this?
  2. Can you show other structures that provide eight divisors?
  3. How do divisor structures relate to factorization?
  4. Why do these specific forms yield eight divisors?
  5. Could there be a different number with similar divisors but a different factor structure?

Tip: For numbers with many factors, consider their prime factorization – each form of exponent structure can indicate the divisor count.

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Math Problem Analysis

Mathematical Concepts

Divisors
Prime Factorization
Number Theory

Formulas

Divisor count formula: if n = p1^e1 * p2^e2 * ... * pk^ek, then the number of divisors of n is (e1 + 1)(e2 + 1)...(ek + 1)

Theorems

Divisor function and structures based on prime factor exponents

Suitable Grade Level

Grades 9-11