S:=0;
for i:=3 to 7 do begin
S:=S*10;
S:=S+i;
end;
S:=S*4;

Ответ: 138268

i = 4

S = 3 * 10 = 30

S = 30 + 4 = 34

i = 5

S = 34 * 10 = 340

S = 340 + 5 = 345

i = 6

S = 345 * 10 = 3450

S = 3450 + 6 = 3456

i = 7

S = 3456 * 10 = 34560

S = 34560 + 7 = 34567

S = 34567 * 4 = 138268