/**
 * Engineering notation formatting utilities
 */
/** SI prefixes from yocto to Yotta */
export declare const PREFIXES: string[];
/**
 * Returns a number formatted in a simplified engineering format -
 * using an exponent that is a multiple of 3.
 *
 * @param x - The value to format
 * @param sigFigs - Number of significant figures (default: 3)
 * @param prefix - Whether to use SI prefix instead of exponent (default: true)
 * @returns Formatted string with engineering notation
 */
export declare function engString(x: number, sigFigs?: number, prefix?: boolean): string;