It's not real but does exist, it helps to determine where a plane will drift, you'll see it in math but never on a ruler, and it was first annotated by a man named Euler

I come with cells for you to complete; using numbers and logic I can be beat. What am I?

What is greater than God, more evil than the devil; the poor have it, the rich need it; and if you eat it, you’ll die?

Turn me on my side, and I am everything. Cut me in half, and I am nothing. What am I?

I eat everything, yet have no mouth. I see everything, without eyes Nothing escapes me, everything is in my reach