0.1+0.2+0.3+0.4...+9.7+9.8=( ) 5.0+5.1+5.2+5.3...+9.9+10.0=(
1个回答

0.1+0.2+0.3+0.4...+9.7+9.8

=(0.1+9.8)×98÷2

=485.1

5.0+5.1+5.2+5.3...+9.9+10.0

=(5+10)×51÷2

=382.5