is called "scientific" or "exponential" notation. The E is a separator. The numbers to the left of the E are called the "mantissa", and the numbers to th e right are the "exponent". The value of the whole expression is the product of the mantissa times ten raised to the power of the exponent. Since 10 to the first power is ten, and 1.1 times ten is eleven, the value of the expression is 11.0 .
Obviously there's no reason why you'd ever write eleven in this format -- but it sure is convenient if you need to write 123 trillion!