Consider a system consisting of `n` particles with masses `m_1,m_2,........m_n` and position vectors `vecr_1,vecr_2....vecr_n`, as shown in the figure. The position vector of `CM` of this system is given by

`vecr_(CM)=(m_1vecr_1+m_2vecr_2+...........+m_nvecr_n)/(m_1+m_2+............+m_n)` `= (sum(m_ivecr_i))/(summ_i)`

If masses `m_1,m_2,......` are situated at `(x_1,y_1,z_1),(x_2,y_2,z_3)........,` co-ordinates of CM in the same reference frame will be given by

`vecx_(CM)=(m_1vecx_1+m_2vecx_2+...........)/(m_1+m_2+............)` `= (sum(m_ivecx_i))/(summ_i)`

`vecy_(CM)=(m_1vecy_1+m_2vecy_2+...........)/(m_1+m_2+............)` `= (sum(m_ivecy_i))/(summ_i)`

`vecz_(CM)=(m_1vecz_1+m_2vecz_2+...........)/(m_1+m_2+............)` `= (sum(m_ivecz_i))/(summ_i)`