# Rules for Determining Significant Figures are critical

 Rules for Determining Significant Figures Significant figures are critical when reporting scientific data because they give the reader an idea of how accurately you could actually measure/report your data. **The data is only as reliable as your least significant/accurate measurement 1) ALL non-zero numbers (1,2,3,4,5,6,7,8,9) are ALWAYS significant. 2) ALL zeroes between non-zero numbers are ALWAYSsignificant. 3) ALL zeroes which are SIMULTANEOUSLY to the right of the decimal point AND at the end of the number are ALWAYS significant.(see Atlantic & Pacific rule below) 4) ALL zeroes which are to the left of a written decimal point and are in a number >= 10 are ALWAYS significant.. (see Atlantic & Pacific rule below) **A helpful way to check rules 3 and 4 is to write the number in scientific notation. If you can/must get rid of the zeroes, then they are NOT significant. The Atlantic/Pacific Rule for Determining Significant Figures 1) look for the Presence, or Absence, of a decimal point - this will tell you which side to start counting from Pacific: left Atlantic: right Pacific Atlantic 2) if there is a decimal point (Presence) you start counting from the left side of the number - starting from the very left side of the number - look for the first non-zero number - count the first non-zero number and every number (0-9) after that - example: 0.00030 - because there is a decimal point (Present), we start from the left side of the number left →0.00030, and look for the first non-zero number 0.00030 - count that number and every number after that regardless of what the number is (0-9) - in this case there are 2 significant figures - 0.00030 3) if there is not a decimal point (Absence) you start counting from the right side of the number - starting from the very right side of the number, look for the first non-zero number - count the first non-zero number and every number (0-9) after that - example: 789000 - because there is no decimal point (Absent), we start from the right side of the number 789000 ← right, and look for the first non-zero number 789000 - count that number and every number after that regardless of what the number is (0-9) - in this case there are 3 significant figures - 789000Download 82.11 Kb.Share with your friends: