feat: add topic content resources

* Update how-computers-calculate@GDLKJkKgB-i7n0YcV2NDa.md

I have added short description so that learner should not roam and can get overview of the topic.

* Update src/data/roadmaps/computer-science/content/how-computers-calculate@GDLKJkKgB-i7n0YcV2NDa.md

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Co-authored-by: Arik Chakma <arikchangma@gmail.com>

src/data/roadmaps/computer-science/content/how-computers-calculate@GDLKJkKgB-i7n0YcV2NDa.md

@@ -1,5 +1,7 @@
 # How Computers Calculate?
 
+Computers calculate using the binary system, where all data is represented as 0s and 1s. These binary states correspond to the ON/OFF positions of transistors, which are the building blocks of logic gates (AND, OR, NOT). Numbers, characters, and instructions are broken into binary sequences (bits), and grouped into bytes (8 bits). Arithmetic operations like addition are performed through logic gates, which combine binary values. The CPU executes these calculations by following a fetch-decode-execute cycle. Complex calculations, such as handling decimals, use floating-point representation. Programs written in high-level languages are compiled into machine code for the CPU to execute.
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 Visit the following resources to learn more:
 
 - [@video@How computers calculate - ALU](https://youtu.be/1I5ZMmrOfnA)