Montana is about 6 times smaller than Algeria.

Algeria is approximately 2,381,740 sq km, while Montana is approximately 376,979 sq km, making Montana 15.83% the size of Algeria. Meanwhile, the population of Algeria is ~44.2 million people (43.2 million fewer people live in Montana).
Tip: This to-scale comparison of Algeria vs. Montana uses the Mercator projection, which distorts the size of regions near the poles.