Euro Triangulation Converter

Euro Triangulation Converter

When the euro arrived, Council Regulation (EC) No 1103/97 froze every legacy currency to a six-significant-digit rate against the euro and made the conversion arithmetic itself a matter of law: converting Deutsche Mark to French francs means going through the euro, with the rounding at each step prescribed — because a one-step "cross rate" produces amounts that are off by a centime, and off-by-a-centime is illegal on an invoice. You are building that converter; archival modules that restate historical documents still need it, and the tests hold you to the letter of the regulation.

Requirements

The starter ships a table named "Euro Fixed Rate" — keep its name, fields and primary key exactly as they are, because the grading tests write rows into it directly:

A row means: 1 euro equals "Units per EUR" units of that currency (e.g. 1.95583 for the Mark, 1936.27 for the lira), and "Amount Rounding Precision" is the currency's smallest expressible unit — the tests only ever seed 0.01 (centesimal currencies) or 1 (the lira has no decimals).

Complete the codeunit named "Euro Triangulation" with one public procedure:

procedure ConvertCurrency(FromCurrencyCode: Code[10]; ToCurrencyCode: Code[10]; Amount: Decimal): Decimal

The euro itself is identified by the literal currency code EUR and never has a row in the table — recognize it by code.

Wherever a rule below says round, it means: round to the nearest multiple of the stated precision, and when the value sits exactly halfway between two multiples, round up — away from zero (Article 5 of the regulation; amounts here are never negative, so "up" and "away from zero" coincide).