Definition of significant figures in English English dictionary
Those digits in an observed quantity (measurement) that are known with certainty plus the first digit that is uncertain
Students should always quote their final answer to an accuracy consistent with the accuracy of the figures given in the question So, if the numbers you are given to work with are only accurate to 3 sig figs then your answer can't be more accurate, no matter how many decimal places appear on your calculator screen
all digits between and including the first non-zero digit from the left, through the last digit [Bevington, 4] (e g 0 05070 has 4 significant figures )
the number of digits reported in a measurement, irrespective of the location of the decimal place