# Examples


## Invoice line total with VAT

```ts
import { dec, add, mul, div, round, toPG, isPeriodic } from "@primebrick/decimal";

const unit = dec("19.99");
const qty = dec(3);
const line = mul(unit, qty);                // 59.97

const vatRate = dec("0.22");
const vat = round(mul(line, vatRate), 2);   // 13.19 (HALF_UP)
const total = add(line, vat);               // 73.16
```

## Splitting a bill (periodicity-aware)

```ts
const total = dec("100.00");
const guests = 3;

const share = div(total, guests);           // 33.3333333333333333 (PG scale)
isPeriodic(share);                          // true — non-terminating

const shareRounded = round(share, 2);       // 33.33 — for display
// remainder: total - shareRounded*guests = 0.01 → assign cents explicitly
const remainder = sub(total, mul(shareRounded, guests)); // 0.01
```

## Money in/out of PostgreSQL

```ts
// numeric column → Decimal
const amount = fromPG(row.amount);          // row.amount: "1234.56"

// Decimal → numeric parameter
await db.query("UPDATE invoices SET total = $1", [toPG(total)]);
```

## Comparison

```ts
cmp("1.0", "1")     // 0  — same value
eq("1.0", "1")      // true
strictEq("1.0", "1")// false — different scale
min("5", "3.9")     // 3.9
max(price, ZERO)    // clamp to non-negative
signum(balance)     // -1 | 0 | 1
```

## Scale control

```ts
round("2.675", 2)                 // 2.68 — exact, unlike Number(2.675).toFixed(2)
setScale("5", 2)                  // 5.00 — pad for display
normalize("5.000")                // 5 — strip zeros
trunc("9.99")                     // 9
floor("-1.2")                     // -2
```