B = | b₁₁ .......... b₁q |

| |

| bp 1 .......... bp q |

then A + B shall denote the p × q series matrix whose members are ah k + bh k.

2⁰ If we have two matrices

A = | a₁₁ .......... a₁q |

| |

| ap 1 .......... ap q |

B = | b₁₁ .......... b₁r |

| |