Think of a water pipe: making the pipe twice as long makes it harder for water to flow through (more resistance), and making it half as thin further restricts the flow, compounding the difficulty significantly.

L-A-R: Length Above, Area under Resistance (Length numerator, Area denominator)

According to the resistance formula $R = \rho \frac{l}{A}$, where $R$ is resistance, $\rho$ is resistivity, $l$ is length, and $A$ is cross-sectional area, doubling the length ($l' = 2l$) and halving the area ($A' = \frac{A}{2}$) results in a new resistance $R' = \rho \frac{2l}{A/2} = 4 \rho \frac{l}{A} = 4R$.

Always check whether dimensions are given as radius or diameter when calculating the cross-sectional area ($A = \pi r^2$ or $A = \frac{\pi d^2}{4}$). Changes in radius square the effect on area!