Scientific notation is a method of representing very large and very small numbers in the form a × 10n, where a is a value between 1 and 10, and n is a nonzero integer. For example, the number 927,000,000 is written in scientific notation as 9.27 × 108. The rules of exponents are used to perform operations with numbers in scientific notation.
Estimation is the process of rounding numbers before performing operations to make operations easier. Estimation can be used when an exact answer is not necessary or to check work.
To round a number, first identify the digit in the specified place value. Then look at the digit one place to the right. If that digit is 4 or less, keep the digit in the specified place value the same. If that digit is 5 or more, add 1 to the digit in the specified place value. All the digits to the right of the specified place value become zeros.