- A quadrilateral with four equal
sides that meet at right angles.
- To square something is to multiply it by itself. To take the square
root is the reverse process. A square number
is the square of a whole number. A well known formula for the difference
of squares is a2 - b2 =
(a + b)(a - b). This formula enables some
otherwise difficult calculations to be done easily in the head. For
example, 43 × 37 = (40 + 3)(40 - 3) = 402 - 32
= 1600 - 9 = 1591.