Buttonswap-PeripheryTechnical ReferencelibrariesSafeMathOn this pageSafeMathFunctionsaddfunction add(uint256 x, uint256 y) internal pure returns (uint256 z);subfunction sub(uint256 x, uint256 y) internal pure returns (uint256 z);mulfunction mul(uint256 x, uint256 y) internal pure returns (uint256 z);