Russia 8 класс Informatics (basic)
Chapters: 2
1. Theoretical foundations
Number systems · Elements of logic
- Number Systems and Encoding – A number system is a way to write numbers using a set of digits and a base. Decimal (base 10) uses 0–9, binary (base 2) uses 0 and 1, octal (base 8) uses 0–7, and hexadecimal (base 16) uses 0–9 and A–F. To go from decimal to any base, divide repeatedly by the base and read remainders bottom to top; for fractions, multiply by the base and read the integer parts top to bottom. To go to decimal, multiply each digit by its place value and add. Binary ↔ octal uses groups of 3 bits, binary ↔ hex groups of 4. Text is stored with encoding schemes: ASCII (7-bit, 128 characters), ISCII (8-bit, Indian scripts) and Unicode (every script), stored as UTF-8 (1–4 bytes) or UTF-32 (4 bytes).
- Boolean Logic – Boolean logic works with only two values: 1 (true) and 0 (false). Logic gates act on them: NOT flips a value; AND gives 1 only if all inputs are 1; OR gives 1 if any input is 1; NAND and NOR are the opposites of AND and OR; XOR gives 1 when inputs differ. A truth table lists the output for every input combination (2ⁿ rows for n inputs). De Morgan's laws: (A·B)' = A' + B' and (A + B)' = A'·B'. Gates joined together form logic circuits that match Boolean expressions.
2. Algorithms and programming
Algorithms and executors · Algorithmic constructions · Programming language basics · Branching and loops · String processing · Algorithm analysis
- Introduction to Problem Solving – Problem solving on a computer has stages: analyse the problem (inputs, outputs, rules), develop an algorithm (a finite, clear, ordered set of steps), code it in a programming language, test it with different inputs, and debug (find and remove errors). An algorithm can be shown as a flowchart (oval = start/stop, parallelogram = input/output, rectangle = process, diamond = decision, arrows = flow) or as pseudocode (structured plain English). Decomposition breaks a big problem into smaller sub-problems that are solved separately and then joined.
- Programming Basics: Sequence, Selection, Loops and Functions – A program is a set of exact instructions a computer follows. Every program is built from three structures: sequence (steps in order), selection (if/else choices) and iteration (loops). Variables store values. Functions group code into reusable, named blocks, which makes programs modular and easier to test, debug and maintain.
- Branching and Loops: Making Programs Decide and Repeat – Branching (if/else) lets a program choose a path using a condition; a loop repeats steps while a condition is true. With these two ideas we can find the biggest number, solve a quadratic, add the digits of a number, test for primes and compute the GCD with Euclid's algorithm.
- Strings in Python – A string is an immutable sequence of characters written in single, double or triple quotes. Each character has a positive index (0 from the left) and a negative index (−1 from the right). Operations: + (concatenation), * (repetition), in / not in (membership) and slicing s[start:stop:step], which takes characters from start up to but not including stop. Traversal means visiting each character with a for or while loop. Built-in methods like len(), upper(), lower(), title(), capitalize(), count(), find(), index(), replace(), split(), join(), strip(), startswith(), endswith(), isalpha(), isdigit(), isalnum(), islower(), isupper() and isspace() return new values without changing the original string.