Diagram of simple filtration: oversize particles in the feed cannot pass through the lattice structure of the filter, while fluid and small particles pass through, becoming filtrate.
An odd function can be identified by replacing both the x and y values with -x and -y values. If the values in your equation are the opposite (positives are negatives and negatives are positives), then the function is odd. Take, for example, this equation y = x^2.
In that class, one student was left out, so 3 is an odd number. An odd number represents a group of paired items with one left out. In other words, odd numbers aren't evenly divisible by 2. When we added one more student to the class, we got an even number of students. But add yet another one, and we're back to one student left out: So, just like even numbers, we can generate odd numbers by adding 2 to an already odd number. We just did that by adding 2 to the odd number 3.