Answer
$\frac{1111}{500}$
Work Step by Step
1. We can identify the sequence as geometrical with $a_1=2, r=\frac{1}{10}$
2. We have $\sum_{j=1}^42(\frac{1}{10})^{j-1}=2\times\frac{1-(\frac{1}{10})^4}{1-(\frac{1}{10})}=\frac{1111}{500}$
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