The Learning Portal: Math: Basic Tutorials: Order of Operations Line 1: Note that fraction bars act as grouping symbols, so the expressions in the numerator and denominator are treated as if they are in brackets. This means that the expression with a numerator of 4 plus 8 over a denominator of 5 minus 3 is the same as open bracket 4 plus 8 close bracket divided by open bracket 5 minus 3 close bracket.