[Danny]

Save the number somewhere.

Код:

new number = (1000 + random(9999));
format(str, sizeof str,"Your number is: %d.",number);
SendClientMessage(playerid, COLOR, str);
CheckNum[playerid] = number;

Then, check the number at the command with:

Код:

if(CheckNum[playerid] == enterednumber) // the number that's entered behind the signcheck cmd.