Unnamed

$\text{Efficient resistance of resistors in series is given by}\\ R_s = R_1+R_2+R_3+\ldots+R_n \\ \therefore R_s = 10000+10000+10000+10000+10000+10000+10000+10000=8\times10000=80000 \\ \dfrac{1}{R_p} = \dfrac{1}{R_1}+\dfrac{1}{R_2}+\ldots+\dfrac{1}{R_n}\\ \therefore \dfrac{1}{R_p} = \dfrac{8}{R} \\ R_p = \dfrac{R}{8}\\ R_s=R_p\\ 80000=\dfrac{R}{8}\\ R = 80000\times 8=640000$

When resistors are in a series their resistance is compounded onto each other as the current must travel through each resistor in succession. So 8 resistors of 10k ohms is 80k ohms.

When resistors are parallel their resistance is split between each other as the current will split up and travel through each resistor individually. So 8 identical resistors of unknown ohms parallel to each other is x/8 ohms.

80,000= $\frac{x}{8}$

x=8(80,000)

x=64,000.