The math category includes numeration, linear counting, base 10, operations, memorization, geometry, fractions and decimals, measurement, time and money, greater than less than, rounding and estimation, and place value. I’m sure we’ll think of more avenues of math to add here!
Montessori math is very strong and the materials are extremely helpful for making abstract concepts concrete.
There are a few concepts that I have not found Montessori lessons for:
Greater than, less than
Place value (although the concept is reinforced in the material)
Rounding and estimation
You may find other gaps as well in your own experience.