## square- 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*a*^{2}-*b*^{2}= (*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) = 40^{2}- 3^{2}= 1600 - 9 = 1591.
Squaring a whole number (integer) gives an integer result, but taking the square root of a whole number often does not. And, as the Greek mathematician Pythagoras and his coworkers discovered, there is not always a rational number expressible as the ratio of two integers) that when squared will equal a particular integer. The square root of 4 is 2 (both integers), but the square root of 2 is somewhere between 1.4142 and 1.4143. The square root of 2 cannot be computed exactly and is called an irrational number.
## Related category• POLYGONS | |||||

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