The unit of number is wei

[sc0Vu]

The unit of number is wei if we don't use 0x prefix.

Maybe transform automatically if user just enter number.

See this transaction just send 1 wei.

https://rinkeby.etherscan.io/tx/0x63929e3e23352dffbd2b67eea779c10d0fc26c6dc5a22e368e66d996c0a42d46