Scientific notation

Numbers in scientific notation are expressed as multiples of powers of 10 (X × 10y).
y is an exponent and can be negative or positive.
y can be any real number (negative or positive).  

X is a number between one and ten
Thus x has only one digit before its decimal point

Example: 1200 is expressed 1.2 × 103

Numbers larger than one expressed in scientific notation have positive powers of 10.  
The number known by chemists as Avogadro's number is VERY large: 
602 200 000 000 000 000 000 000 
To express in scientific notation:
Enter 6.022
Then count the number of places by which the decimal point has been moved to the left from its original position.
Final answer: 6.022 × 1023
 
Numbers smaller than one expressed in scientific notation have negative powers of 10.
The radius of a hydrogen atom is equal to 0.000000000073 m.
To express in scientific notation:
Enter 7.3
Then count the number of places by which the decimal point has been moved to the right from its original position.
Final answer: 7.3 × 10–11