Finance

Validate the checksum of a Bitcoin address (Base58Check / Bech32 / Bech32m).

Identify the payment brand from a card number's IIN and run the Luhn check.

Expected work for a vanity prefix on a Bitcoin (base58) or Ethereum (hex) address.

Validate or apply the EIP-55 mixed-case checksum for any Ethereum address.

Validate an IBAN's country length and ISO 13616 mod-97 checksum.

Search the active ISO 4217 currency codes, numbers and minor units.

Estimate how long it takes for an investment to double (72 / rate).

Calculate sales tax, markup vs margin and retail pricing in one place.

Side-by-side: simple, compounded and continuously-compounded growth.

Compute cost basis on a sale using FIFO, LIFO or average-cost methods.

Validate a US bank routing number's checksum and identify the Federal Reserve region.