someone's number is up the time has come when someone is doomed to die or suffer some other disaster or setback. informal

☞ This phrase may allude to a lottery number or to the various biblical passages referring to the 'number of your days', i.e. the length of your life, for example in Job 38:21: 'Knowest thou it, because thou wast then born? or because the number of thy days is great?'