numad: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/numad - from package: numad

You may install the required package with command yum install {package}

Error in other languages:
numad: bevel nie gevind nie
numad: comandă negăsită
numad: comando não encontrado
numad: commande introuvable
numad: command not found
numad: käsku ei ole
numad: không tìm thấy lệnh
numad: komanda nerasta
numad: Kommando nicht gefunden.
numad: kommandot finns inte
numad: komut yok
numad: nie znaleziono polecenia
numad: níor aimsíodh an t-ordú
numad: no se encontró la orden
numad: no s'ha trobat l'ordre
numad: opdracht niet gevonden
numad: parancs nem található
numad: perintah tidak ditemukan
numad: príkaz nenájdený
numad: příkaz nenalezen
numad: команда не найдена
numad: командата не е открита
numad: 命令找不到
numad: コマンドが見つかりません