6.4×0.99
=6.4×(1-0.01)
=6.4×1-6.4×0.01
=6.4-0.064
=6.336
7.6×2.02
=7.6×(2+0.02)
=7.6×2+7.6×0.02
=15.2+0.152
=15.352