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Problem 1


Problem 1


Multiples of 3 and 5

If we list all the natural numbers below $10$ that are multiples of $3$ or $5$, we get $3$, $5$, $6$ and $9$. The sum of these multiples is $23$.

Find the sum of all the multiples of $3$ or $5$ below $1000$.


3或5的倍数

在小于$10$的自然数中,$3$或$5$的倍数有$3$、$5$、$6$和$9$,这些数之和是$23$。

求小于$1000$的自然数中所有$3$或$5$的倍数之和。