/////
// CommonJS:

// From the Umbrella ethers package...
const { BigNumber } = require("ethers");

// From the bignumber pacakge...
const { BigNumber } = require("@ethersproject/bignumber");


/////
// ES6 and TypeScript:

// From the Umbrella ethers package...
import { BigNumber } from "ethers";

// From the bignumber pacakge...
import { BigNumber } from "@ethersproject/bignumber";