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Pascal's Triangle

Each entry C(n,k) = n!/(k!(n-k)!) counts ways to choose k from n. Row n sums to 2^n; shallow diagonals give Fibonacci numbers.

Concept Fundamentals
C(n,k) = n!/(k!(n-k)!)
Binomial coeff
2^n
Row sum
C(n,k) = C(n-1,k-1) + C(n-1,k)
Recursive
In diagonals
Fibonacci

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The pattern appeared in China (Yang Hui ~1000 AD) before Pascal published in 1653. Coloring odd numbers black produces the Sierpinski triangle fractal. The hockey stick pattern: diagonal sums equal the number where the diagonal ends.

Key quantities
C(n,k) = n!/(k!(n-k)!)
Binomial coeff
Key relation
2^n
Row sum
Key relation
C(n,k) = C(n-1,k-1) + C(n-1,k)
Recursive
Key relation
In diagonals
Fibonacci
Key relation

Ready to run the numbers?

Why: Pascal's triangle gives coefficients for (x+y)^n, counts combinations, and connects to probability.

How: Each entry is the sum of the two above. Row n gives coefficients of (x+y)^n.

The pattern appeared in China (Yang Hui ~1000 AD) before Pascal published in 1653.Coloring odd numbers black produces the Sierpinski triangle fractal.

Run the calculator when you are ready.

Gateway to CombinatoricsBinomial coefficients and beyond
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COMBINATORICS

Pascal's Triangle โ€” Gateway to Combinatorics

Generate the triangle, compute C(n,k), explore row sums, hockey stick, and binomial theorem connections.

๐Ÿ”บ Common Examples โ€” Click to Load

Mode

pascal_triangle.sh
CALCULATED
$ calc --rows=8
Rows
8
Row Values
1, 7, 21, 35, 35, 21...
Row Sum (2^n)
128
Number of Elements
36
Share:
Pascal's Triangle Calculator
8 rows generated
2^7 = 128
numbervibe.com/calculators/mathematics/sequences/pascal-triangle

Pascal's Triangle

1
11
121
1331
14641
15101051
1615201561
172135352171

Row Values (Bar)

Row Sums Growth (2^n)

Coefficient Distribution (Doughnut)

Step-by-Step Breakdown

CONSTRUCTION
Row 01 (by definition)
Row 11 1
Row 21 2(=1+1) 1
Row 31 3(=1+2) 3(=2+1) 1
Row 41 4(=1+3) 6(=3+3) 4(=3+1) 1
Row 51 5(=1+4) 10(=4+6) 10(=6+4) 5(=4+1) 1
Row 61 6(=1+5) 15(=5+10) 20(=10+10) 15(=10+5) 6(=5+1) 1
Row 71 7(=1+6) 21(=6+15) 35(=15+20) 35(=20+15) 21(=15+6) 7(=6+1) 1

For educational and informational purposes only. Verify with a qualified professional.

๐Ÿงฎ Fascinating Math Facts

๐Ÿ’

The hockey stick: sum along a diagonal equals the number where it ends.

11โฟ

Concatenating row n gives 11^n for small n (e.g., 14641 = 11^4).

Key Takeaways

  • C(n,k) = n!/(k!(n-k)!) โ€” each entry is the number of ways to choose k from n
  • Row sum = 2^n โ€” the nth row sums to 2 raised to the power n
  • Fibonacci in diagonals โ€” add numbers along shallow diagonals to get 1,1,2,3,5,8...
  • Symmetry โ€” C(n,k) = C(n,n-k); each row is symmetric around its center
  • The nth row gives coefficients of (x+y)n(x+y)^n in the binomial expansion

Did You Know?

๐Ÿ“œPascal didn't discover it โ€” the pattern appeared centuries earlier in China (Yang Hui ~1000 AD), India, and Persia (Al-Karaji). Pascal published his treatise in 1653.Source: Wikipedia
๐Ÿ’The 'hockey stick' pattern: start at any 1 on the edge, go diagonally, sum the numbers โ€” the total appears in the next row.Source: Cut-the-Knot
11โฟFor small n, concatenating row n gives 11^n. Row 4: 1,4,6,4,1 โ†’ 14641 = 11^4. Breaks down when digits carry.Source: Khan Academy
๐Ÿ”บColoring odd numbers black and even white produces the Sierpinski triangle fractal pattern.Source: Fractals
๐Ÿ“ŠC(n,k) connects to the binomial theorem: (x+y)^n expansion uses row n coefficients. Used in probability (binomial distribution) and combinatorics.Source: NCTM
๐ŸŽฒProbability distributions: P(k successes in n trials) uses C(n,k). Pascal's triangle gives these coefficients directly.Source: Statistics

How Pascal's Triangle Works

1. Binomial Coefficients

The number at (n,k) = (nk)=n!k!(nโˆ’k)!\binom{n}{k} = \frac{n!}{k!(n-k)!} โ€” ways to choose k items from n.

2. Recursive Construction

(nk)=(nโˆ’1kโˆ’1)+(nโˆ’1k)\binom{n}{k} = \binom{n-1}{k-1} + \binom{n-1}{k} โ€” each entry is the sum of the two above.

3. Binomial Theorem

(x+y)n=โˆ‘k=0n(nk)xnโˆ’kyk(x+y)^n = \sum_{k=0}^{n} \binom{n}{k} x^{n-k} y^k โ€” row n gives expansion coefficients.

Expert Tips

Finding Patterns

Look for Fibonacci in diagonals, powers of 11 in concatenated rows, and Sierpinski when coloring odd/even.

Combinatorics Shortcuts

Use Pascal's triangle instead of computing factorials โ€” C(n,k) is at row n, position k.

Connection to Probability

Binomial distribution: P(k successes in n trials) โˆ C(n,k). Row n gives all coefficients.

Binomial Expansion

For (x+y)^n, use row n. Row 6: 1,6,15,20,15,6,1 โ†’ (x+y)^6 = x^6 + 6x^5y + 15x^4y^2 + ...

Comparison Table

FeatureThis CalculatorManualProgramming
Visual triangleโœ…โš ๏ธ Tediousโš ๏ธ Code needed
Binomial C(n,k)โœ…โŒ Factorial overflow riskโœ…
Row sum verificationโœ…โŒโœ…
Step-by-stepโœ…โŒโŒ
Chartsโœ…โŒโš ๏ธ Code needed
Copy & Shareโœ…โŒโŒ
Educational contentโœ…โŒโŒ

FAQ

What is C(n,k)?

C(n,k) = n!/(k!(n-k)!) is the number of ways to choose k items from n distinct items. Same as "n choose k" or combinations.

Why does each row sum to 2^n?

There are 2^n subsets of an n-element set. Each subset has some size k, and C(n,k) counts subsets of size k. Sum over k = 2^n.

What is the hockey stick pattern?

Start at a 1 on the left or right edge, move diagonally inward. The sum of numbers along that diagonal equals the number where the diagonal ends.

How does Pascal relate to probability?

Binomial distribution: P(k successes in n trials) uses C(n,k). Pascal's triangle gives these coefficients.

What is the Sierpinski connection?

Color odd numbers one color, even another. A fractal (Sierpinski triangle) emerges.

Why is it called Pascal's Triangle?

Blaise Pascal wrote a comprehensive treatise in 1653, though the pattern was known earlier in China, India, and Persia.

Can I use negative n or k?

For this calculator, n and k are non-negative integers. Generalized binomial coefficients exist for real n.

What is the maximum n?

We support n up to 100 for binomial coefficients. For full triangle, up to 30 rows for performance.

Where do Fibonacci numbers appear?

Add numbers along shallow diagonals (top-left to bottom-right). The sums 1,1,2,3,5,8... form the Fibonacci sequence.

Infographic Stats

~1000 AD
Discovered (China/India)
20+
Known patterns
Fibonacci
In diagonals
2^n
Row sum

Disclaimer: This calculator provides mathematically precise binomial coefficients. For very large n, floating-point limits may apply. Educational use.

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