## anonymous 5 years ago What is the sum of the first 55 positive multiples of 3? Please show your work.

1. anonymous

$3+6+9+\cdots+162+165$ $=3(1)+3(2)+ \cdots + 3(54)+3(55)$ $=3(1+2+3+ \cdots +54+55) = 3 \cdot \frac{55(56)}{2}=4620$

2. anonymous

Nice! I should've thought of that one. Thanks

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