Significant figures are all the number of digits reported in a measurement, including all certain digits in a measurement plus one uncertain digit (always the last digit).
The more precise a measurement is, the more significant digits it will have, but the last digit is always the one uncertainty, it is always a measurement.
Rules:
1)All numbers (excluding zero) are ALWAYS significant. e.g. 1234 has 4 sigfigs
2)Zeros at the beginning of a number are NEVER significant, they merely indicate the location of the decimal point. e.g 0.0000012 has 2 sigfigs
3)Zeros at the end of a number (BEFORE the decimal point) are NEVER significant. e.g. 50000 has 1 sigfig
4)Zeros at the end of a number (AFTER the decimal point) are ALWAYS significant. e.g. 5.000 has 4 sigfigs
5)Digits between two significant digits are ALWAYS significant. e.g. 5000.3 has 5 sigfigs
Rounding Rules, oooooohhhhh...
1) To round, always look at the digit to the right of the one you wish to round
2) If that digit is greater than 5, round up. If that digit is less than 5, round down
3) If that digit IS 5, and there are nonzero digits after it (symbolizing that it is in fact MORE than half), round up
4) if that digit IS 5, and ends at five, round so that the last digit is even (either up or down depending on the situation) e.g. 1.235 rounded to the nearest hundredth is 1.24
Adding and Subtracting
1) Round the answer to the fewest number of decimal places. e.g. 1.234 + 567.98=569.21 < We can only be accurate to the hundredth position
Multiplying and Dividing
1) Round the answer to the fewest number of sigfigs. e.g. 1.3 x 15462.2 = 2.0 x 10^4 < When we tried to round 20 100.86 to two sigfigs, our result was 20 000. This only has one sigfig, so the best way to fix this would be to express 20 000 in scientific notation, thereby making sure that two sigfigs (2.0) are represented.
KEKEKE.
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