Significant digits are numerical figures that carry meaning to present precise measurements. This is especially useful in mathematics and chemistry. Rounding off numbers is a convenient technique that we always apply because it keeps lengthy numbers to a comfortable length. An answer from one solution could be used to find another parameter using another solution. When you round off the numbers as early as the first step of many solutions, your final answer becomes less precise. Precision is the quality of being exact or accurate. Hence, your calculations could bring error to whatever you're doing. To minimize error, scientists have established rules for convention. These rules tell which numbers are significant and in what situations do they become significant.