nnum: 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 Debian possible default full paths are:

/usr/bin/nnum - from package: stda

You may install the required package with command apt-get install {package}

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