Formula for Entire Column

Okay so I am doing an estimating project and I am wondering if there is a way to make a formula for an entire column? Each row the numbers would be different, Column E is my quantity and I is my unit cost, J being my material cost(quantity times unit costs or E*I), so can I do this once and make it follow the pattern in the rest of the rows? I was close to it, but it was using the same quantity base for all of the calculations