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Question 6712: Adjacent Exact Factorials and Their Ratio

On this page
  1. Original question and givens
  2. Definition and scope
  3. Step-by-step derivation
  4. Reverse checks
  5. Result
  6. This question review and source binding

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← Question derivation index · Original question batch

R0012-06712 · q-20261010-advance-20261014-r05-factorial-0012

Original question and givens

N begins at 0, F(0)=0!=1, and factorials use exact integer arithmetic, not floating point. n=11. Give decimal integers (F(n), F(n+1), F(n+1)/F(n)).

  • G001 — N begins at 0, F(0)=0!=1, and factorials use exact integer arithmetic, not floating point. n=11. Give decimal integers (F(n), F(n+1), F(n+1)/F(n)).

Definition and scope

Use the original question domain, assumptions and cited MKO definitions. This item has second-context mathematical and bilingual review, with the model, answer and every arithmetic step independently recomputed from the original parameters; the source question remains a candidate.

Step-by-step derivation

S001 · implies

Before

N includes0;F(0)=1;F(j)=j·F(j−1)

After

exact integer products,not floating values or a permutation proof

Conditions: none

Use empty product1 and integer factor multiplication,retaining large values exactly.This finite recurrence audit is not a general proof of permutation counting.

Step identifiers and dependencies

Rule: exact_factorial_protocol · Uses: G001

S002 · implies

Before

actual factorial:start at F(0)

After

F(0)=1

Conditions: none

The product of zero factors is1,not0;this is the successor recurrence's base.

Step identifiers and dependencies

Rule: factorial_empty_product_base · Uses: G001, S001

S003 · calculation

Before

actual factorial through factor1 := mul(1, 1)

After

actual factorial through factor1 = 1

Conditions: none

Multiply the preceding factorial by the new positive integer factor,retaining every exact intermediate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

actual factorial through factor2 := mul(1, 2)

After

actual factorial through factor2 = 2

Conditions: none

Multiply the preceding factorial by the new positive integer factor,retaining every exact intermediate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · calculation

Before

actual factorial through factor3 := mul(2, 3)

After

actual factorial through factor3 = 6

Conditions: none

Multiply the preceding factorial by the new positive integer factor,retaining every exact intermediate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S004

S006 · calculation

Before

actual factorial through factor4 := mul(6, 4)

After

actual factorial through factor4 = 24

Conditions: none

Multiply the preceding factorial by the new positive integer factor,retaining every exact intermediate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

actual factorial through factor5 := mul(24, 5)

After

actual factorial through factor5 = 120

Conditions: none

Multiply the preceding factorial by the new positive integer factor,retaining every exact intermediate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · calculation

Before

actual factorial through factor6 := mul(120, 6)

After

actual factorial through factor6 = 720

Conditions: none

Multiply the preceding factorial by the new positive integer factor,retaining every exact intermediate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · calculation

Before

actual factorial through factor7 := mul(720, 7)

After

actual factorial through factor7 = 5040

Conditions: none

Multiply the preceding factorial by the new positive integer factor,retaining every exact intermediate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · calculation

Before

actual factorial through factor8 := mul(5040, 8)

After

actual factorial through factor8 = 40320

Conditions: none

Multiply the preceding factorial by the new positive integer factor,retaining every exact intermediate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S009

S011 · calculation

Before

actual factorial through factor9 := mul(40320, 9)

After

actual factorial through factor9 = 362880

Conditions: none

Multiply the preceding factorial by the new positive integer factor,retaining every exact intermediate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S010

S012 · calculation

Before

actual factorial through factor10 := mul(362880, 10)

After

actual factorial through factor10 = 3628800

Conditions: none

Multiply the preceding factorial by the new positive integer factor,retaining every exact intermediate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S011

S013 · calculation

Before

actual factorial through factor11 := mul(3628800, 11)

After

actual factorial through factor11 = 39916800

Conditions: none

Multiply the preceding factorial by the new positive integer factor,retaining every exact intermediate.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S012

S014 · calculation

Before

true successor factorial := mul(12, 39916800)

After

true successor factorial = 479001600

Conditions: none

Compute F(n+1)=(n+1)F(n).

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S013

S015 · calculation

Before

successor factorial ratio := div(479001600, 39916800)

After

successor factorial ratio = 12

Conditions: none

Since F(n)>0,division is legal and the exact ratio is n+1.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S014

S016 · implies

Before

F(11)=39916800>0;F(12)=479001600

After

ratio=12

Conditions: none

This includes n=0 with F(0)=F(1)=1,without0!=0 or floating approximations.

Step identifiers and dependencies

Rule: positive_factorial_adjacent_ratio · Uses: G001, S015

Reverse checks

  • S016 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S015 · premise_and_result_audit — Recompute successor factorial ratio with exact rational arithmetic, not rounded decimals.
  • S014 · premise_and_result_audit — Recompute true successor factorial with exact rational arithmetic, not rounded decimals.
  • S013 · premise_and_result_audit — Recompute actual factorial through factor11 with exact rational arithmetic, not rounded decimals.
  • S012 · premise_and_result_audit — Recompute actual factorial through factor10 with exact rational arithmetic, not rounded decimals.
  • S011 · premise_and_result_audit — Recompute actual factorial through factor9 with exact rational arithmetic, not rounded decimals.
  • S010 · premise_and_result_audit — Recompute actual factorial through factor8 with exact rational arithmetic, not rounded decimals.
  • S009 · premise_and_result_audit — Recompute actual factorial through factor7 with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Recompute actual factorial through factor6 with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute actual factorial through factor5 with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute actual factorial through factor4 with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Recompute actual factorial through factor3 with exact rational arithmetic, not rounded decimals.
  • S004 · premise_and_result_audit — Recompute actual factorial through factor2 with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute actual factorial through factor1 with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

(39916800, 479001600, 12)

The full substitutions and premise checks give the original answer; source identity,format and status are unchanged.

This question review and source binding

Review date: 2026-10-26

Original questions, answers, step expressions, numeric ASTs and historical records are retained. Source candidate labels remain historical and are not overwritten as formal proof.

Source hashes and review receipts
  • input commit: 0f7be61e2c22317a4075561dc822c87d881a50db
  • original question SHA-256: e549cfe38ef87044659dc3744e2ff5bc9c758d7ff5db10829f569a9fa863a420
  • candidate record SHA-256: c12e7a1fe67830c98b6c6be2c09d456d052c5b3ab5b270b2cb8cbe9fdbd45356
  • semantic review receipt SHA-256: 90dbc494b2d34ef51f412dcff63cfcc1a2215d038bff71f38f5dded4c64faf00
  • question-first witness SHA-256: b72a3b8bcf10f584396e0dd5198c657b0934a71864e5a3fa6321d7a613aef9f9
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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