Читать книгу Foundations of Chemistry - Philippa B. Cranwell - Страница 40

1 7.5 × 5.7 = 42.75 = 43 = 4.3 × 101The smallest number of significant figures is two, so this becomes 43 after reducing the number of significant figures and rounding.

2 (6.4 × 102) × (1.30 × 104) = 8.32 × 106 = 8.3 × 106The smallest number of significant figures is two, so 8.32 becomes 8.3 after reducing the number of significant figures.

3 (1.751 × 10−3) × (59.0 × 10−2) = 103.309 × 10−5 = 1.033 09 × 10−3 = 1.03 × 10−3The smallest number of significant figures is three, so 1.03309 becomes 1.03 after reducing the number of significant figures.

4  = 4.9 × 101The smallest number of significant figures is two, so 4.948 × 101 becomes 4.9 × 101 after reducing the number of significant figures and rounding down. This would normally be written as 49.