What is a surd? How would you go by simplifying a surd?

A surd is an irrational square root which cannot be reduced to a whole number when squared. When you think of the square root of 4, the answer is 2. When you think of the square root of 9, the answer is 3. However, the square root of 5 cannot be simplified into a whole number (the answer will be between 2 and 3).

When simplifying a surd (such as the square root of 40) an easy method is to try and find two multiples of the number you are trying to simplify and try to square root those two numbers individually. 

Hint:the square root of 40 will equate to the square root of 4 times the square root of 10.