= 1.5+5. 1+66×( 10-0. 1)

=6.6+66× 10-66×0. 1

=6.6+660-6.6

=660

1.2÷0.7+ 1.5÷0.7+2.2÷0.7

=( 1.2+ 1.5+2.2)÷0.7

=4.9÷0.7

=7

2.2×2.3+3.3× 1.8

= 1. 1×2×2.3+ 1. 1×3× 1.8

= 1. 1×(4.6+5.4)

= 1. 1× 10

= 1 1

7.2×0.5+0.52×7.2

=7.2×(0.5+0.52)

=7.2×( 1+0.02)

=7.2× 1+7.2×0.02

=7.2+0. 144

=7.344