习题 1指出下列各数是几位有效数字: (1)1.0001 (2)0.001 (3)自然数1 (4)9.800 (3)常数 (1)5 (2)1 (4)4 2把下列各数修约成有三位有效数字: (1)1.0751 (2)0.86249 (3)27.052 (4)3.1415 (5)0.002000 (6)0.463500 ?6 10 (7)52.65 (8)10.8000 (9)8.971× 解: (1)1.08 (2)0.862 (3)27.1 (4)3.14 (5)0.00200 (6)0.464 (7)52.6 (8)10.8 (9)8.97 × 10 ?6 3改错: (1)N = (10.8000 ± 0.2)cm N = (10.8 ± 0.2)cm q (2) = (1.61248 ± 0.28765) × 10 ?19 C q = (1.61 ± 0.29) × 10 ?19 C (3)28cm=280mm 28cm = 2.8 ×10 mm 2 (4)E = (1.93 ×10 ± 6.79 ×10 ) N / m 11 9 2 E = (1.93 ± 0.07) ×10 N / m 11 2 (5) R = 6371km = 6371000m R = 6371km = 6.371×10 m 6 4按有效数字规则计算: (1)107.50-2.5= 105.0 (2) 98.754 ÷ 1.3 = 0.76 ×10 300 × 300×1500 5 = 4.5 ×10 (3) 11.60 ? 10.6 (4)(2.480 ? 2.2) × 5.989 = 0.84 2 2.00 8.0421 (5) + 30.9 = 2 ×103 6.038 ? 6.034 5