如何设置宽度，以便它可以除以某个值

I need to create table with width 90% of page. But I also need to make special grid. Some cells are 2*3, some 2*1, some 3*2, 1*1 and so on. "1" is one ninth of table width. So, my target is to delete gaps between cells, they appear because of rounding. What is the best way to achieve it? I have already made html code with required colspans and rowspans. It takes the required form if I set width 33.33% for cell with colspan 3 and so on. I need to create table with width 90% of page.