A) var s, i, n :integer;
begin
s:=0;
readln(n);
for i:= 1 to n do s:=s+i;
writeln(s);
end.
б) var s, i, n :integer;
begin
s:=0;
readln(n);
for i:= 1 to n do s:=s+(i*i);
writeln(s);
end.
в) var s, i, n :integer;
begin
s:=0;
readln(n);
for i:= 1 to n do
begin
if (i mod 2 = 0) then s:=s+i;
end;
writeln(s);
end.
г) var s, i :integer;
begin
s:=0;
for i:= 10 to 99 do s:=s+i;
writeln(s);
end.
Вот)