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Question

1+3+5+7+…+999999=?

Comments

$500000^2=?$

$1+3=[(3+1)/2]^2=4$

$1+3+5=[(5+1)/2]^2=9$

$1+3+5+7=[(7+1)/2]^2=16$

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1+3+5+7+…+999999=?