Module 8 (M8) - Algebra - Surds Surds are irrational numbers containing a square root sign. They are square roots of numbers that are not square. Irrational numbers cannot be expressed as fractions.

Then there was root-mean-square (RMS) voltage. For those nice sine waves, you took the peak voltage and divided by the square root of two, 1.414 or so. You know that kid in the front of the class?