98.766×987.68-98.765×987.69
=0.001×987.68+98.765×987.68-98.765×987.69
=0.001×987.68+98.765×(987.68-987.69)
=0.001×987.68-98.765×0.01
=0.98768-0.98765
=0.00003
98.766×987.68-98.765×987.69
=0.001×987.68+98.765×987.68-98.765×987.69
=0.001×987.68+98.765×(987.68-987.69)
=0.001×987.68-98.765×0.01
=0.98768-0.98765
=0.00003