Added new file in C

[isuri9734]

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Description 📜

• I have added Calculator program C. I have tried it in if-else statement.

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Type of change 📝

• [x] Code
• [ ] Documentation (Content Creation in the form of codes or tutorials)
• [ ] Notes (Handwritten notes, cheatsheets, presentations, mind-maps)
• [ ] Web Dev Projects
• [ ] Others (If you choose other, Please mention changes below)

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Programming Language

• [ ] C#
• [x] C
• [ ] Python
• [ ] Java
• [ ] Javascript
• [ ] Others

Domain of Contribution 📊

• [ ] Introduction
• [ ] Data Structures
• [ ] Algorithms
• [ ] Competitive Programming
• [x] Mathematics
• [x] Others

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