PC141 Study Guide - Final Guide: Roundoff, Scientific Notation, Significant Figures
Document Summary
Leading or trailing zeroes can make it hard to determine number of significant figures: 2500, 0. 000036: each of these has two significant figures. Scientific notation writes these as a number from 1 10 multiplied by a power of 10, making the number of significant figures much clearer: 2500 = 2. 5 103: if we write 2. 50 103, it has three significant figures. The last digit in a calculated number may vary depending on how it is calculated, due to rounding off of insignificant digits: example: . 21 + 8% tax = . 3868, rounds to . 39. . 35 + 8% tax = . 458, rounds to . 46. 1 m = 3. 281 ft (this is a conversion factor) 316 ft (1 m/3. 281 ft) = 96. 3 m. Note that the units cancel properly this is the key to using the conversion factor correctly! 1. as a check for a detailed calculation if your answer is very different from your estimate, you"ve probably made an error.
