suma a 4 nr consecutive este 342:⇔a+a+1+a+2+a+3=342⇔4a+6=342⇔4a=342-6⇔4a=336⇔a=336:4⇒a=84 ;b=84+1=85;c=84+2=86;d=84+3=87 verificare:84+85+86+87=342. suma a 5 nr pare cons.este 470⇔a+a+2+a+4+a+6+a+8=470⇔5a+20=470⇔5a=470=20⇔5a=450⇔a=450:5⇔a=90;b=90+2=92;c=90+4=94;d=90+6=96;e=90+8=98 verificare:90+92+94+96+98=470