Consider a linear block code with $n=8,k=4.$ The parity bits of linear block code is obtained as:

$b_0=m_1+m_2+m_3$

$b_1=m_0+m_1+m_2$

$b_2=m_0+m_1+m_3$

$b_3=m_0+m_2+m_3$

Where $m_0,m_1,m_2,m_3,$ and $b_0,b_1,b_2,b_3$ are the parity check bits.