Calculate the area of a rectangle if its length and width are equal: 6.2 dm and 2.8 dm.

In accordance with the general rule, which is accepted and widespread in mathematical science, the area of a rectangle is determined as the product of its two sides, i.e. product, determined by multiplying the value of its length by the value of its length. Thus, for the rectangle presented in the original task, we have:

S = a * b;

S = 6.2 * 2.8 = (6 + 0.2) * (2 + 0.8) = 6 * 2 + 6 * 0.8 + 0.2 * 2 + 0.2 * 0.8 = 12 + 4.8 + 0.4 + 1.6 = 12 + 4.8 + 2 = 14 + 4.8 = (10 + 4) + (4 + 0.8) = 18 + 0.8 = 18, eight.