0.0645×2300+0.78×645-6.45
=6.45×23+78×6.45-6.45
=6.45×(23+78)-6.45
=6.45×100-6.45
=645-6.45
=638.55
0.0645×2300+0.78×645-6.45
=0.0645*100*23+0.78*100*6.45-6.45
=6.45*23+78*6.45-6.45
=6.45*(23+78-1)
=6.45*(23-1+78)
=6.45*(22+78)
=6.45*100
=645
0.0645×2300+0.78×645-6.45
=6.45×23+6.45×78-6.45
=6.45×(23+78-1)
=6.45×100
=645