=2682.6+27

=2709.6

Keep three significant figures: 2.7 1× 10 cubic.

②:(23.2﹢4.2)×3.42-3.7

= 27.4×3.42-3.7

=93.708-3.7

=90.008

Keep three significant figures: 90.0.

③:﹣5.2×﹙2.6- 1.24﹚﹢2.2×﹙﹣ 1.6﹚

=-5.2× 1.36+(-3.52)

=-7.072-3.52

=- 10.592

Keep three significant digits: 10.6.

④:6.23﹣﹙4.26-3. 19﹚×﹙﹣5.2﹚

=6.23- 1.07×(-5.2)

= 6.23+5.564

= 1 1.794

Keep three significant digits: 1 1.8.

⑤:372÷ 15﹢42× 12.6

=24.8+529.2

=554

Keep three significant figures: 554.