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Mathematics

Sum Calculator

Sum Calculator

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For a quick sum of consecutive integers: sum = (first + last) × count / 2. Sum of 1 to 100: (1+100) × 100/2 = 5,050.

Difficulty:Beginner

Did you know?

Carl Friedrich Gauss, aged 10, reportedly summed 1 to 100 instantly by noticing that 1+100=101, 2+99=101, and so on, making 50 pairs: 50×101=5,050. This elegant insight led to the formula n(n+1)/2.

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Reviewed May 2026
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