Some numbers involving roots, such as √2, √3, cannot be expressed exactly in the form of a fraction. Any

number of the form n√a, which cannot be written as a fraction of two integers is called a surd.

Whilst numbers like √2 have decimal approximations which can be obtained using a calculator,

e.g √2 = 1.414 . . . , you must remember that these are approximations, whereas the form √2 is exact.

So, writing a number in surd form involves writing it in terms which are exact, such as √2 or √3

Example: write √48 in surd form

48 = 3*16

so √48 = √3 * √16

= √3 * 4

or, as it's usually written 4 √3

So, reduce the square root down into simpler terms called surds.