# format(_:) Formats a decimal value using this style. ``` func format(_ value: Decimal) -> String ``` ## Parameters `value` The decimal value to format. ## Return Value A string representation of `value` formatted according to the style’s configuration. ## Discussion Use this method when you want to create a single style instance and then use it to format multiple decimal values. The following example creates a style that uses the `en_US` locale and then adds the [`scientific`](/documentation/Foundation/NumberFormatStyleConfiguration/Notation/scientific) modifier. It then applies this style to all of the decimal values in an array. ```swift let scientificStyle = Decimal.FormatStyle( locale: Locale(identifier: "en_US")) .notation(.scientific) let nums: [Decimal] = [100.1, 1000.2, 10000.3, 100000.4, 1000000.5] let formattedNums = nums.map { scientificStyle.format($0) } // ["1.001E2", "1.0002E3", "1.00003E4", "1.000004E5", "1E6"] ``` To format a single floating-point value, use the [`Decimal`](/documentation/Foundation/Decimal) instance method [`formatted(_:)`](/documentation/Foundation/Decimal/formatted(_:)), passing in an instance of [`Decimal.FormatStyle`](/documentation/Foundation/Decimal/FormatStyle), or [`formatted()`](/documentation/Foundation/Decimal/formatted()) to use a default style. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)