512*7+488*7=7000
512 488 3584
×7 ×7 +3416
---------- --------- -----------
3584 3416 7 000
960*8+140*8=8 800
960 140 7 680
×8 ×8 +1 120
--------- --------- ----------
7 680 1 120 8 800
800*4-450*4=1400
800 450 3200
×4 ×4 -1800
-------- ------- --------
3200 1 800 1400
3*350-3*150=
350 150 1050
×3 ×3 -450
-------- ------- ---------
1050 450 600