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Question 34153: Quotient of Permutation and Combination Counts

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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R0067-34153 · q-20260930-r06-permutation-combination-quotient-0003

Original question and givens

For selection of k=0 distinct objects without replacement from n=2, compute the exact integer quotient P(n,k)/C(n,k). The empty selection counts once.

  • G001 — For selection of k=0 distinct objects without replacement from n=2, compute the exact integer quotient P(n,k)/C(n,k). The empty selection counts once.

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

source roles = [qf-permutation-combination-quotient, [k, n, operation]]

After

derived = [quotient, no-invented-domain]

Conditions: none

Check THIS bank’s keys/operation/domain:legacy table underscores,MOD50 local hyphens;permissive BASE data acquires no unknown-field restriction.Keep Number.isInteger and SAFE source guards distinct,while preserving ORIGINAL JSON number representations.

Step identifiers and dependencies

Rule: R67_SOURCE_specific_keys_operation_domain_and_numeric_bank · Uses: G001

S002 · implies

Before

source roles = [2, 0]

After

derived = [[], 1]

Conditions: none

Choose ordered positions from n DISTINCT objects WITHOUT replacement.Position i has n−i+1 choices.For k=0,the empty selection counts ONCE and the product starts at1.THIS bank permits n≤200,not another bank’s32/64 cap.

Step identifiers and dependencies

Rule: Selection_DISTINCT_no_replacement_order_and_EMPTY_convention · Uses: G001, S001

S003 · calculation

Before

Quotient ORIGINAL permutations divided by subset orderings := div(1, 1)

After

Quotient ORIGINAL permutations divided by subset orderings = 1

Conditions: none

Calculate exactly from ORIGINAL ordered operands.Legacy derived integers are not recapped at the RAW SAFE bound;MOD50 rationals separately retain the NAIVE pre-reduction source envelope.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

Quotient ORIGINAL permutations over combinations := div(1, 1)

After

Quotient ORIGINAL permutations over combinations = 1

Conditions: none

Calculate exactly from ORIGINAL ordered operands.Legacy derived integers are not recapped at the RAW SAFE bound;MOD50 rationals separately retain the NAIVE pre-reduction source envelope.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · implies

Before

source roles = [2, 0, 1, 1]

After

derived = [1, 1]

Conditions: none

EVERY k-element subset has exactly k! orderings.Ordered selections partition into equal fibers over their underlying subsets,so P=C*k!,C>0,and P/C=k!.At k=0 this remains1/1=1,not an estimated ratio or probability.

Step identifiers and dependencies

Rule: Selection_EVERY_k_subset_has_k_factorial_orderings · Uses: G001, S004

Reverse checks

  • S005 · premise_and_result_audit — Reverse-audit THIS step against the ORIGINAL roles,complete premises and field order.Distinguish implication from equivalence;preserve originals,English,MKOs,ASTs and review states.Finite checks are not independent review or general formal proof.
  • S004 · premise_and_result_audit — Recompute Quotient ORIGINAL permutations over combinations with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute Quotient ORIGINAL permutations divided by subset orderings with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Reverse-audit THIS step against the ORIGINAL roles,complete premises and field order.Distinguish implication from equivalence;preserve originals,English,MKOs,ASTs and review states.Finite checks are not independent review or general formal proof.
  • S001 · premise_and_result_audit — Reverse-audit THIS step against the ORIGINAL roles,complete premises and field order.Distinguish implication from equivalence;preserve originals,English,MKOs,ASTs and review states.Finite checks are not independent review or general formal proof.

Result

1

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: 3f7c6144c59ce6659a786930fbb722095bc603a207a4369f5d1b9707502b9d33
  • candidate record SHA-256: d014c5ca37432c8cec149cee717bd1a00aef0f612ae95e63a36110973f02e8bd
  • semantic review receipt SHA-256: c89efa383b67bb2cf25bcf16160b9f5f614bbe5e5e791f4d7f58234d17a3371c
  • question-first witness SHA-256: 12766d451c5375842b4fc2843ae94807ec55f15763a916558026912a13873d57
  • Lean: NOT_RUN · human review: NOT_PERFORMED
Same-source full JSON