77x(77+1)=77x78=77ⅹ(100-22)=7700-77x22=7700-77x20-77ⅹ2=7700-1540-154=6160-154=6006
77×77+77＝77×77+77×1＝77×(77+1)＝77×78＝77×(80-2)＝77×80-77×2＝6160-154＝6006
700-154+7000
（80×77）—3×77+77
72558582758
