How number base conversion works
Every number base uses place values. Decimal uses powers of 10, binary uses powers of 2, octal uses powers of 8, and hexadecimal uses powers of 16. The written symbols change, but the quantity can remain the same.
For programming and computer science, binary and hexadecimal are especially common. Binary shows the exact bit pattern, while hexadecimal compresses each four-bit group into one readable symbol. Decimal is easier for humans to compare, so many workflows involve moving between all three.