6.NOS.C.6: Represent a rational number as a point on vertical or horizontal number lines. Represent points on a number line with negative numbers. a. Estimate quantities by reasoning about their location on a number line, their relationship to benchmark numbers, and by rounding. b. Locate and interpret the positions of rational numbers on a number line. c. Recognize and locate opposite signs of rational numbers as indicating locations on opposite sides of 0 on the number line.