Cześć ;-)
a)
[tex]4\cdot12=4\cdot(10+2)=4\cdot10+4\cdot2=40+8=\boxed{48}\\\\23\cdot2=(20+3)\cdot2=20\cdot2+3\cdot2=40+6=\boxed{46}\\\\3\cdot22=3\cdot(20+2)=3\cdot20+3\cdot2=60+6=\boxed{66}\\\\11\cdot6=(10+1)\cdot6=10\cdot6+1\cdot6=60+6=\boxed{66}[/tex]
b)
[tex]15\cdot5=(10+5)\cdot5=10\cdot5+5\cdot5=50+25=\boxed{75}\\\\7\cdot31=7\cdot(30+1)=7\cdot30+7\cdot1=210+7=\boxed{217}\\\\54\cdot4=(50+4)\cdot4=50\cdot4+4\cdot4=200+16=\boxed{216}\\\\4\cdot27=4\cdot(20+7)=4\cdot20+4\cdot7=80+28=\boxed{108}[/tex]
c)
[tex]3\cdot60=3\cdot(50+10)=3\cdot50+3\cdot10=150+30=\boxed{180}\\\\110\cdot2=(100+10)\cdot2=100\cdot2+10\cdot2=200+20=\boxed{220}\\\\4\cdot250=4\cdot(200+50)=4\cdot200+4\cdot50=800+200=\boxed{1000}\\\\5\cdot130=5\cdot(100+30)=5\cdot100+5\cdot30=500+150=\boxed{650}[/tex]
d)
[tex]125\cdot2=(100+25)\cdot2=100\cdot2+25\cdot2=200+50=\boxed{250}\\\\4\cdot152=4\cdot(100+50+2)=4\cdot100+4\cdot50+4\cdot2=400+200+8=\boxed{608}\\\\3\cdot550=3\cdot(500+50)=3\cdot500+3\cdot50=1500+150=\boxed{1650}\\\\2\cdot707=2\cdot(700+7)=2\cdot700+2\cdot7=1400+14=\boxed{1414}[/tex]
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