You can write number literals in a number of ways. First off, you have typical decimal format, but additionally there are prefixes for hexadecimal and binary numbers. Unlike many languages, there is no special format for octal literals. You can optionally use an underscore to separate digit groups as desired. For example:
A :: 10; // here's a 10
C :: 0b10; // this is 2 in binary
B :: 0x10; // and this is 16 in hexadecimal
D :: 0b1010_0010_0101_1111;
E :: 0xFFFF_FF_FF; // This is inconsistent and weird, but legal.
F :: 16_777_216;