Assuming this is referring to which is more important to understand/master, I do agree that multiplication is more important to understand/master because it leads to the understanding/mastering of division. Although, division should follow logically from multiplication - putting multiple equal parts together makes a "whole" should lead to "taking away" equal parts a given number of times - the connection seems to be "lost" after long division is turned over to a calculator. Those that truly master multiplication seem to make faster calculations that lead to more quick completion of assignments. I think this creates a more positive experience with math and makes it more enjoyable for the student which leads to further success. It is easier to turn a division problem into multiplication than vice versa. Example: "8 divided by 2" becomes "what times 2 is 8?" not so much with "5 times 2" becoming "what divided by 2 is 5?" Also, it has been my experience that students struggling with math at the 7th grade level or higher (up through college) tend to have a multiplication deficit. This deficit flows into fractions, understanding powers of 10, etc. and deepens the disconnect to other areas of math.

To my mind, multiplication is more important as it provides the logical base for further forward operations. If you know multiplication, you build up from smaller units to larger units and can perform other operations upon the whole or upon parts of the whole. Most importantly, if you know multiplication then you already know division because division is the reverse operation of multiplication. For instance, if you know that 33 times 65 is 2145, then you automatically know that 2145 divided by 65 is 33. And, yes, the reverse can be said: if you know the division of the whole, then you automatically know the multiplication of the parts. Nonetheless, the logical order is to build from the parts to the whole rather than to deconstruct from the whole to the parts.