A/L ICT Lesson 03 Practice Tool: How Data are Represented in Computers

This is a practice tool for Unit 3 of the Sri Lankan GCE Advanced Level ICT syllabus, Grade 12, on how data are represented inside computers. It covers the four number systems and their bases (binary, octal, decimal and hexadecimal), converting numbers between bases including fractional values, representing negative numbers with sign-magnitude, one's complement and two's complement, the range of an n-bit two's complement number, floating point representation with its mantissa and exponent, character encoding standards such as BCD, ASCII, EBCDIC and Unicode, and the bitwise logical operations AND, OR, XOR and NOT. The unit is calculation-heavy and usually carries 3 to 5 MCQ marks and 10 to 15 marks on Paper II.

Sixteen activities are grouped into five modules: matching drills for number systems and encoding standards, flip cards for quick value recall, step-sequencing tasks for decimal-to-binary and two's complement, a fill-in form for practising conversions yourself, sorting exercises for zero representation and bitwise results, a true-or-false swipe on common misconceptions, and timed quizzes. Your score is kept in your browser, so you can close the page and come back to it.

The tool opens in English. Tap the language button to switch the whole tool to Sinhala. Both languages use the same terms as the Lesson 3 notes, so what you practise here matches what you read there.