A 5X16 = 5x(10+6)=5x10+6x5=50+30=80
6X12 = 6x(10+2)=6x10+6x2=60+12=72
B 4X22 = 4x(20+2)=4x(10+10+2)=4x10+4x10+4x2=40+40+8=88
7X23 = 7x(20+3)=7x(10+10+3)=7x10+7x10+7x3=70+70+21=161
C 4X234 = 4x(200+30+4)=4X200+4x30+4x4=800+120+16=936
6X142= 6x(100+40+2)=6x100+6x40+6x2=600+240+12=852
