Question

2+3+4+......+30=cu cat trebuie sa folosim suma lui gause

Answer 1

2+3+4+......+30 =
=(1+2+3+4+...+30) - 1
=[30x(30+1)]:2 - 1
=(30x31) :2 - 1
=930:2-1
=465-1
=464