Max Product for Sums of 16
Hints:
-
Start simple: Try experimenting with small total sums like 4, 5, 6, and see what combinations of numbers give the largest product.
-
Use only 2s and 3s: Any number 4 or greater can be broken down into a sum involving only 2’s and 3’s. For example:
-
Replace 4 with 2 + 2
-
Replace 5 with 2 + 3
-
-
Compare strategies:
-
Is it better to use two 3’s (which sum to 6) or three 2’s (which also sum to 6)?
-
3×3=9
-
2×2×2=8
-
So: two 3’s are better!
-
-
-
General idea: Try to break your total sum into as many 3’s as possible, and use a 2 only when necessary.
Solution and Exploration:
Let’s start by experimenting with smaller numbers before tackling 16. Working through small cases helps us spot patterns and strategies.
Sample Breakdowns:
-
1 = 1 → Product = 1
-
2 = 2 → Product = 2
-
3 = 3 → Product = 3
-
4 = 2 + 2 → Product = 4
-
5 = 2 + 3 → Product = 2 × 3 = 6
-
6 = 3 + 3 → Product = 3 × 3 = 9
-
7 = 2 + 2 + 3 → Product = 2 × 2 × 3 = 12
-
8 = 2 + 3 + 3 → Product = 2 × 3 × 3 = 18
-
9 = 3 + 3 + 3 → Product = 3 × 3 × 3 = 27
-
10 = 2 + 2 + 3 + 3 → Product = 2 × 2 × 3 × 3 = 36
Observations:
-
Numbers greater than 4 should be broken into smaller parts—especially 2’s and 3’s.
-
Avoid using 1 unless absolutely necessary—it lowers the product.
-
Replace 4 with 2 + 2, since it doesn’t change the product but fits our pattern better.
-
Always replace 2 + 2 + 2 (product = 8) with 3 + 3 (product = 9)—a better outcome.
General Strategy:
-
If the number is even, start by expressing it as a sum of 2’s.
-
If it’s odd, start with a 3, then break the rest into 2’s.
-
Every time you have three 2’s (2 + 2 + 2), replace them with two 3’s.
Applying the Strategy:
-
16 = 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2
→ Grouped as 2 + 2 + (3 + 3) + (3 + 3)
→ Product = 2 × 2 × 3 × 3 × 3 × 3 = 324
Larger Numbers (Efficient Form):
-
20
→ Best breakdown: 2 + 3 × 6
→ Product: 2 × 3⁶ = 2 × 729 = 1458 -
50
→ Best breakdown: 2 + 3 × 16
→ Product: 2 × 3¹⁶ -
100
→ Best breakdown: 4 × 3³²
→ (e.g., 2 + 2 + 3 × 32)
→ Product: 4 × 3³²
This approach gives you the maximum product for a given sum using whole numbers—by leveraging the optimal use of 2’s and 3’s.