The total number of ways to choose 4 marbles from 16 is: - Treasure Valley Movers

The Total Number of Ways to Choose 4 Marbles from 16: The Science Behind Combinations

When faced with the question — “How many ways can you choose 4 marbles from a set of 16?” — many might initially think in terms of simple counting, but the true elegance lies in combinatorics. This article explores the exact mathematical answer, explains the concept of combinations, and reveals how you calculate the total number of ways to select 4 marbles from 16.

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Understanding the Problem

At first glance, choosing 4 marbles from 16 might seem like a straightforward arithmetic problem. However, the key distinction lies in whether the order of selection matters:

• If order matters, you’re dealing with permutations — calculating how many ways marbles can be arranged when position is important.
  - But if order doesn’t matter, and you only care about which marbles are selected (not the sequence), you’re looking at combinations.

Since selecting marbles for a collection typically concerns selection without regard to order, we focus on combinations — specifically, the number of combinations of 16 marbles taken 4 at a time, denoted mathematically as:

$$
\binom{16}{4}
$$

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What is a Combination?

A combination is a way of selecting items from a larger set where the order of selection is irrelevant. The formula to compute combinations is:

$$
\binom{n}{r} = \frac{n!}{r!(n - r)!}
$$

Where:
- $ n $ = total number of items (here, 16 marbles)
- $ r $ = number of items to choose (here, 4 marbles)
- $ ! $ denotes factorial — the product of all positive integers up to that number (e.g., $ 5! = 5 \ imes 4 \ imes 3 \ imes 2 \ imes 1 = 120 $)

Using this formula:

$$
\binom{16}{4} = \frac{16!}{4!(16 - 4)!} = \frac{16!}{4! \cdot 12!}
$$

Note that $ 16! = 16 \ imes 15 \ imes 14 \ imes 13 \ imes 12! $, so the $ 12! $ cancels out:

$$
\binom{16}{4} = \frac{16 \ imes 15 \ imes 14 \ imes 13}{4 \ imes 3 \ imes 2 \ imes 1}
$$

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Calculating the Value

Now compute the numerator and denominator:

• Numerator:
  $ 16 \ imes 15 = 240 $
  $ 240 \ imes 14 = 3,360 $
  $ 3,360 \ imes 13 = 43,680 $

• Denominator:
  $ 4 \ imes 3 = 12 $, $ 12 \ imes 2 = 24 $, $ 24 \ imes 1 = 24 $