Answer:
6
Step-by-step explanation:
Aops question
We have $\frac29 + \frac17 = \frac{14}{63} + \frac{9}{63} = \frac{23}{63}$. Expressing $\frac{23}{63}$ as a decimal using long division, we find $\frac{23}{63}=0.\overline{365079}$. Therefore, every 6th digit after the decimal point is a 9. So, the 18th digit is a 9; the 20th digit is 2 decimal places later, so it is a $\boxed{6}$.
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