Measurement Notes Chapter 2:1

Measurement  A way to describe the world with numbers  Answers questions such as how long, how much, or how far.

Estimation  A rough measurement of an object  You use prior knowledge to help you with an estimation  Comparison is a good way to create an estimation  Used to check if your answer is reasonable  Use the word “about”

Precision and Accuracy  Precision is a description of how close measurements are to each other …The SMALLER the measure the MORE precise  EX: a second hand is more precise than a minute hand  Accuracy is when you compare a measurement to a real, actual, or accepted value.  EX: a watch which is not set correctly is NOT accurate

Rounding  If the digit to the right is 0,1,2,3, or 4, the digit being rounded stays the same  If the digit is 5,6,7,8, or 9, the digit rounded increases by 1  The digits to the right of the digit being rounded to are deleted if they are also to the right of the decimal. If they are to the left of the decimal, they are changed to zero. How we would round to the tens place?   

Rounding Examples Round 217 to the nearest hundred Round 800 to the nearest hundred Round 564 to the nearest ten Round 295 to the nearest ten Round 725 to the nearest ten Round 959 to the nearest hundred Round 252 to the nearest ten Round 618 to the nearest hundred Round 928 to the nearest ten Round 732 to the nearest hundred Round 163 to the nearest ten Round 21 to the nearest ten

Significant Digits Example# of Significant Digits Rule 4533All non-zero digits ARE always significant 50574Zeros between 2 significant digits ARE significant 5.003Additional zeros to the right of decimal and a significant digit ARE significant Placeholders are NOT significant Initial (beginning zeros) are NOT significant The number of digits that truly reflect the precision of the number are called significant figures. The Rules are as follows:

Mrs. Rector Note To Self: Atlantic and Pacific

Rules for Sig. Figs.  Rules For Significant Digits  Digits from 1-9 are always significant.  Zeros between two other significant digits are always significant  One or more additional zeros to the right of both the decimal place and another significant digit are significant.  Zeros used solely for spacing the decimal point (placeholders) are not significant.  Recognizing significant digits will become much easier over time, as you continue to practice the rules. Below are some examples, which show the number of significant digits in a group of numbers, and an explanation why the digits are significant. 3All non-zero digits are always significant 5057 L4Zeros between 2 sig. dig. are significant kgAdditional zeros to the right of decimal and a sig. dig. are significant Placeholders are not sig.

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