Question

ajutor!!dau coroana!!3 & 4

Answer 1

398*457 - 398*456 = 398*(457-456) = 398*1 = 398

1456*345 + 1456*655 = 1456*(345+655) = 1456*1000 = 1456000

237*346 + 346*49 - 346*285 = 346*(237+49-285) = 346*1 = 346

99*1457 + 99*457 - 99*1914 = 99*(1457+457-1914) = 99*0 = 0

35*99 + 35 = 35*(99+1) = 35*100 = 3500

107*43 + 107*56 + 107 = 107*(43+56+1) = 107 * 100 = 10700

46*39 + 46*47 + 86*32 + 86*23 = 46*(39+47) + 86*(32*23) = 46*86 + 86*55 = 86*(100+1) = 8600 + 86 = 8686

2+4+6+...+20 = 2*(1+2+3+4+...+10)= 2*55=110

bafta!