Binary numbers always start with a ‘0b’ or ‘0B’ sequence, followed by one or more binary digits. Binary digits are only the digits 0 and 1.
So, 0b111011010100 is a valid binary number, but 0b111011210100 is not, since it contains a character which is not a valid binary digit.
The largest binary number currently supported in Rittle can have 64 binary digits.
Additionally, it is worth mentioning that binary numbers are always unsigned.