What is positional notation and how does it apply to the decimal (base 10) system?

Positional notation means a digit's value depends on its position; in base 10 each position is a power of 10 (ones, tens, hundreds, ...).

Positional notation means the value of a digit depends on its position in the number.

Decimal (Base 10) uses powers of 10:

Example: 245

• 2 × 100 = 200
• 4 × 10 = 40
• 5 × 1 = 5
• Total = 245

Go deeper:

• Wikipedia — Positional notation — why a digit's value depends on its place, with worked base-10/2/16 examples.