Exact-fraction mineral ownership

The problem

Mineral interests are fractions: an undivided 1/3, a 1/16 royalty, 3/8 of 7/8. Spreadsheets store them as floating-point decimals. Each conversion loses a little; each multiplication compounds it. Across a chain with a dozen conveyances and a handful of reservations, the total drifts away from one, and a report that should show an exact over-conveyance shows 0.99999 or 1.00001 instead.

Why "round to four places" is not a fix

Rounding hides the drift; it does not remove it. A rounded total of 1.0000 can conceal an interest that is genuinely over-conveyed by 1/1024 — a fraction that becomes acres on a large tract and dollars on a producing lease.

Exact arithmetic

Represent every interest as a rational number with arbitrary-precision integers — a numerator and a denominator that never overflow and never round. Then 1/3 + 1/3 + 1/3 is exactly 1; 1/3 of 160.33 acres is 16033/300 acres all the way to the report; and an over-conveyance is reported as exactly what it is: "over by 1/4".

Balance checking

With exact fractions, "does this tract's ownership total one?" becomes a yes-or-no question. An interest that does not total to one is flagged, not rounded away. Net mineral acres are computed from exact fractions and only then rendered as decimals for the workbook, with the fraction kept beside them.

Money too

Day rates, expenses and invoices are integer cents for the same reason: 0.1 + 0.2 is not 0.3 in floating point, and a landman's invoice should not depend on it.

In TitleDesk

Interests are stored and computed as BigInt rationals throughout the ownership screen, the acreage ledger and the reports. Mineral title research software.

Bring your assignment, recorded instruments and client format. TitleDesk brings the research, source pages, runsheet, ownership calculations and report package into one workspace, so you can spend more time examining title and serving your clients. Download TitleDesk or talk to Spencer.

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