>>11220046only as accurate as least accurate measure, adding/subtracting decimals the lowest decimal count controls sig figs, multiplying/dividing the lowest sig fig count controls sig figs, generally nonzero digits signal the beginning of sig figs, if you have 4000 there is only one sig fig present, but with 400.0 there are 4 sig figs present, 0.000345 there are 3 sig figs. if you add and divide in a calculation the lower of the two sig fig counts decided between the decimal rule for addition and sig fig rule for mult/divide will determine final sig fig count. always underline the last sig fig from each calculation instead of rounding early. there is little else to say its just common sense you can’t count degrees of accuracy you couldn’t have reasonably estimated and you need to indicate where your estimate occurred hence underlying the last sig fig
