Paying bills from Litecoin: why the order of returns matters
Version: spending-path-20261021-v1
Model created 20 October 2026 UTC; 21 October in Warsaw.

WHAT THIS IS
An original deterministic synthetic cash-flow study. It contains no historical
prices, customer accounts, observed transactions, market probabilities or forecast.
The two monthly return lists contain the same values in a different order.
Both start at USD100/LTC and end at USD100/LTC. Investor cash-flow outcomes differ.

SCOPE AND RULES
16 scenarios and 154 monthly ledger rows:
- 12 main cases: two price orders x three cash reserves x two fee models;
- 2 two-month hand examples starting with 3 LTC;
- 2 three-month depletion examples starting with 2.5 LTC.
Each main account starts with USD2000 of total value, including its cash reserve.
Cash reserves of USD0/100/200 correspond to 20/19/18 LTC, not extra wealth.
The reserve is a starting allocation. Creating it through a sale is not simulated.
Apply a month's return first, then pay that month's USD100 bill. Cash is used
first; it earns no interest and is not refilled. Every month is a synthetic index,
not a calendar observation. The no-cost and 1%-of-gross-plus-USD1-per-sale models
are declared fictional charges, not provider fee schedules.

ROUNDING AND CONSERVATION
Python Decimal with 80-digit working precision performs the model arithmetic.
Required gross proceeds = (cash still needed + fixed sale fee)/(1-fee fraction).
Divide by the current price, then round the LTC sale UP to 0.00000001 LTC.
Proportional fee = exact decimal fraction of gross proceeds; fixed fee is applied
once only when a sale actually occurs. Net cash credit is rounded DOWN to USD
cents. Any excess credited cash remains in the account. Any uncredited fractional-
cent remainder is recorded separately. It is not spendable cash or a hidden fee.
These cash rounding rules are modeling conventions, not universal exchange rules.

If available LTC is insufficient, sell what is available only if its net cash
credit is positive, pay the available amount, record the shortfall, and stop later
sales. Subsequent bills are explicitly unpaid. Negative balances, borrowing and
automatic rescue funding are not allowed. This stopping rule is not a household
behavior forecast. Terminal marked value = remaining LTC x terminal price +
retained credited cash. No final liquidation is assumed and no final fee deducted.

REPRODUCE OFFLINE
Use Python3.10+ with its standard library; no installation, API key or network
access is needed. The scripts do not access wallets or place transactions.
Keep all downloaded files together.

  python -B verify.py.txt
  python -B reproduce.py.txt --output reproduced

The reproducer writes only to the explicitly selected output directory and rejects
its own input directory as the output. Compare results.json, summary.csv and
monthly-ledger.csv with the released files. The verifier writes no files, checks
regenerated bytes and independently checks exact-rational ledger identities,
minimum sale rounding, fees, balances, cash carry, shortfalls and negative inputs.
SHA256SUMS.txt covers individual package files. The ZIP and checksum manifest
are excluded from their own checksums to avoid a circular definition.

FILES
inputs.json: frozen assumptions, price-return orders and policy rules.
results.json: summaries plus every monthly ledger row, decimal amounts as strings.
summary.csv / monthly-ledger.csv: the same calculated values for inspection.
reproduce.py.txt: the complete standard-library model; no random simulation.
verify.py.txt: offline reproduction, ledger and file-integrity checks.
bill-planning-checklist.txt: blank private worksheet; no personal data collected.
sources.json: primary context links, actual retrievalUTC, raw-response SHA256 and
claim boundaries. Full regulator HTML snapshots are not distributed.
The SVG figures are calculated model graphics, not observed market charts.
Optional artwork-provenance.json describes the editorial cover and diagrams.

LIMITATIONS
No observed or executable price data; no price probabilities or forecast.
No spread/slippage, minimum trade, order-book depth, withdrawal/network fee,
settlement delay, account restriction, FX, tax, inflation, cash interest, other
income, reserve refill, rebalancing or initial reserve-creation trade.
The synthetic 50% fall/100% rebound is chosen to make arithmetic transparent,
not because it is a representative, typical, probable or predicted LTC path.
The model is not personal financial, tax or retirement advice. It does not
recommend a reserve size or allocation to LTC. The source context does not endorse
our examples. Reproduction validates the stated arithmetic, not future outcomes.

Article: https://litecoin.watch/articles/paying-bills-from-litecoin-why-the-order-of-returns-matters
Corrections: https://litecoin.watch/corrections/