1)
49*51
(50-1)*(50+1)=50²-1²=2500-1=2499
2)
72*68
(70+2)*(70-2)=70²-2²=4900-4=4896
3)
92*88
(90+2)*(90-2)=90²-2²=8100-4=8096
1)
49*51
(50-1)*(50+1)=50²-1²=2500-1=2499
2)
72*68
(70+2)*(70-2)=70²-2²=4900-4=4896
3)
92*88
(90+2)*(90-2)=90²-2²=8100-4=8096