---
title: "-=(_:_:)"
framework: foundation
role: symbol
role_heading: Operator
path: "foundation/decimal/-=(_:_:)"
---

# -=(_:_:)

Subtracts one decimal number from another, storing the result in the first number.

## Declaration

```swift
static func -= (lhs: inout Decimal, rhs: Decimal)
```

## Parameters

- `lhs`: The value to subtract from.
- `rhs`: The value to subtract.

## Discussion

Discussion If the result of this operation requires more precision than the Decimal type can provide, the result is rounded using the NSDecimalNumber.RoundingMode.plain rounding mode. To specify a different rounding mode, use the NSDecimalSubtract(_:_:_:_:) function instead.