Question

вычислите рациональным способом
1)147×85+53×60+147×15+53×40
2)275×32+725×28+275×19+725×22
3)326×67+174×29+326×33+174×71

Answer 1

147×85  + 53×60 + 147×15 +53×40 =
= 147×(85+15)  + 53×(60+40)=
= 147×100  +53×100= 
= 100×(147+53) =100×200=
= 20000

275×32+ 725×28  + 275×19 +725× 22=
= 275× (32+19)  + 725×(28+22)=
= 275 × 51  +  725 ×50 =
= 275× 50   + 275×1  +725×50=
= 50×(275+725) + 275  =
= 50×1000 + 275 =
= 50000 +275=50275

326 × 67 + 174× 29  + 326× 33 + 174× 71 =
= 326× (67+33)  + 174×(29+71)=
= 326×100  + 174×100=
= 100×( 326+174) = 
= 100×500 = 50000