standard_description: Interpret the equation y = mx + b as defining a linear function, whose graph is a straight line; give examples of functions that are not linear. For example, the function A = s2 giving the area of a square as a function of its side length is not linear because its graph contains the points (1,1), (2,4) and (3,9), which are not on a straight line.
problem_activity: Problem 1
Find the following products.
a.   20 × 4
b.   9 × 300
c.   5 × 6,000
Problem 2
Estimate the following products.
a.   8 × 84
b.   458 × 4
c.   2 × 9,340


aligns: no