Why are the numbers 7 x 11 x 13 and 7 x 6 x 5 x 4 x 3 x 2 x 15 considered composite numbers?

A composite number is defined as a positive integer that has at least one positive divisor other than one or itself. In simpler terms, a composite number can be divided evenly by numbers other than just 1 and itself, meaning it has more than two factors.

Let’s analyze the two examples:

1. The number 7 x 11 x 13

Calculating this gives:

  • 7 x 11 = 77
  • 77 x 13 = 1001

So, the result is 1001. Now, let’s look at the factors of 1001:

  • 1
  • 7
  • 11
  • 13
  • 77 (7 x 11)
  • 91 (7 x 13)
  • 143 (11 x 13)
  • 1001 (1 x 1001)

The number 1001 has multiple divisors: 1, 7, 11, 13, 77, 91, 143, and 1001 itself, making it composite.

2. The number 7 x 6 x 5 x 4 x 3 x 2 x 15

Next, let’s evaluate this product:

  • 7 x 6 = 42
  • 42 x 5 = 210
  • 210 x 4 = 840
  • 840 x 3 = 2520
  • 2520 x 2 = 5040
  • 5040 x 15 = 75600

The result is 75600. Now we must consider its factors:

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 10
  • 12
  • 14
  • 15
  • 20
  • 21
  • 28
  • 30
  • 35
  • 42
  • 60
  • 70
  • 84
  • 105
  • 126
  • 140
  • 180
  • 210
  • 252
  • 300
  • 420
  • 630
  • 756
  • 1260
  • 2520
  • 5040
  • 75600

The number 75600 has numerous divisors, including all combinations of its prime factors. Hence, it too is a composite number.

In conclusion, both numbers (1001 and 75600) contain more than two factors, fitting the definition of composite numbers.

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