When a quantity is too large or small for the unit (such that it will require many zeros) we sometimes choose to express it in standard form or scientific notation. It is written as the product of a power of 10 (10^y, y can be +ve or –ve) and a number that is greater than or equal to 1 and less than 10 (1≤ |x| <10), i.e. X × 10^y. In scientific notation, all digits before the multiplication sign are significant.