addition of n number

[lucid plinth]

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[left echo]

there's a simpler formula you can use

if the addition series begins from 1, like 1+2+3+4+.... upto n, you can find the sum using n(n+1)/2

if it starts from a different number, like in your 2nd question, then you can use the same formula and then subtract the extra numbers, in this case -(1+2+3+4) or -(4+(4+1)/2)

@haughty lintel does that help?

[lapis elm]

Are you sure there's 47 pairs? Therein lies the problem. On top of that you could just do what Shroud suggested instead. That's way less errorprone

[haughty lintel]

Thankyou @lapis elm @left echo

[fossil rapids]

@haughty lintel has given 1 rep to @lapis elm @left echo

[haughty lintel]

+close