## Appendix A. Working with Numbers: Binary and Hexadecimal

Understanding how the binary and hexadecimal number systems work is not critical to programming better applications in C++, but it helps you to better understand what happens under the hood.

### Decimal Numeral System

Numbers that we use on a daily basis are in the range of 0–9. This set of numbers is called the Decimal Numeral System. As the system is comprised of 10 unique digits, it’s a system with base of 10.

Hence, as the base is 10, the zero-based position of each digit denotes the power of 10 that the digit is multiplied with. So

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957 = 9 x 10^{2} + 5 x 10^{1} + 7 x 10^{0} = 9 x 100 + 5 x 10 + 7

In the number 957, the zero-based position of 7 is 0, that of 5 is ...