Решение
Пусть 784=a
781*182*783*784+1=a(a-1)(a-2)(a-3)+1=a² *a²-6a*a²-6a+1=(a²-3a+1)²=(784²-3*784+1)²
1) 115/16-10/16=105/16=6 9/16
2) 402/63-270/63=132/63=2 6/63
3) 753/72-614/72=139/72=1 67/72
4) 110/12-69/12=41/12=3 5/12
Вроде бы:
1234= 1000+200+30+4
21,21:7+(200,1:25-2,02:4)=3,03+(8,004-0,505)=3,03+7,499=10,529
1147,5:3-(18,6:15+350,7:7)=382,5-(1,24+50,1)=382,5-51,34=331,16