Rhode Island is about 139 times smaller than Montana.

Montana is approximately 376,979 sq km, while Rhode Island is approximately 2,706 sq km, making Rhode Island 0.72% the size of Montana. Meanwhile, the population of Montana is ~989,415 people (63,152 more people live in Rhode Island).
Tip: This to-scale comparison of Montana vs. Rhode Island uses the Mercator projection, which distorts the size of regions near the poles.