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Measurements A quantity is something that has magnitude, size or amount. A quantity is not the same as a measurement. A quantity represented by a teaspoon is volume, but the teaspoon is a unit of measurement. Base units – Derived units – Accuracy – Precision – Rules for rounding - greater than 5, increase by 1 less than 5, stay the same 5, followed by non-zero digits, increase by 1 5, not followed by non-zero digit(s) and preceded by an odd digit, increase by 1 5, not followed by non-zero digit(s) and preceded by an even digit, stay the same When adding or subtracting decimals, the answer must have the same number of digits to the right of the decimal point as there are in the measurement having the fewest digits to the right of the decimal point. Note:always round after the math has been completed. For multiplication and division, the answer can have no more significant figures that are in the measurement with fewest number of significant figures. Note:always round after the math has been completed. Scientific Notation 1. scientific notation – numbers are written in the form of M x 10n, where the factor “M” is a number greater than or equal to 1 but less than 10 and “n” is a whole number 2. determine “M” by moving the decimal point in the original number to the left or to the right so that only one non-zero digit remains tot the left of the decimal point 3. determine “n” by counting the number of places that you moved the decimal point a. if the decimal is moved to the left, then “n” is positive b. if the decimal is moved to the right, then “n” is negative 4. Mathematical operations using Scientific Notation a. addition and subtraction 1a. these operations can only be done if the values have the same exponent 2a. if the values do not have the same exponent, then one or more of the values needs to be altered so that all values have the same exponent 3a. once the values have the same exponents, then add/subtract the “M” value as normal and nothing is done with exponent at this time 4a. if the new value for “M” is not greater than or equal to 1 or greater than or equal to 10, then you must write the new number correctly b. multiplication 1b. the “M” factors are multiplied 2b. the “n” factors are added 3b. if the new value for “M” is not greater than or equal to 1 or greater than or equal to 10, then you must write the new number correctly c. division 1c. the “M” factors are divided 2c. the “n” factors are subtracted 3c. if the new value for “M” is not greater than or equal to 1 or greater than or equal to 10, then you must write the new number correctly