# Olympiades mathématiques - Mini
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## OMB - Mini 2020

1. Quelle somme vaut 2020?
A) $200+2\cdot10$
B) $20+20\cdot100$
C) $10+10\cdot101$
D) $50+50\cdot20+20$
E) $10\cdot51+50\cdot2$

:::spoiler Solution
:::success
B) $20+20\cdot100=20+2\,000=2020$
:::

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2. $101\,010\cdot73=$
A) $7\,300$
B) $737\,373$
C) $7\,307\,300$
D) $7\,373\,730$
E) $730\,730\,730$

:::spoiler Solution
:::success
D) \begin{align}
101\,010\cdot73&=(100\,000+1\,000+10)\cdot73\\
&=73\cdot(100\,000+1\,000+10)\\
&=73\cdot100\,000+73\cdot1\,000+73\cdot10\\
&=7\,300\,000+73\,000+730\\
&=7\,373\,730
\end{align}
:::

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