a.
uses crt;
var n,i,b:longint;
begin
clrscr;
write('Nhap n: ');readln(n);
for i:=1 to n do b:=b+2*i;
writeln('B=',b);
readln
end.
b.
uses crt;
var n,i:longint; s:real;
begin
clrscr;
write('Nhap n: ');readln(n);
for i:=1 to n do s:=s+1/(2*i-1);
writeln('S=',s:0:3);
readln
end.
c.
uses crt;
var n,i,t:longint;
begin
clrscr;
write('Nhap n: ');readln(n); t:=1;
for i:=1 to n do t:=t*i;
writeln('T=',t);
readln
end.
