Does the deceased benefit from charity and fasting if he died when he was not praying?
Question

 
My father has recently passed away.
He has missed many salaah during his lifetime. He has passed away at aged 65.
Is there any way of paying to charity any amount for the salaah missed.
Please advise how to calculate the number of salaah missed and the amount to pay for charity for each day of salaah missed.
Eg. 65 years less 15 years = 50 years salaah missed. 50 years X 365 days = 18250 days of salaah missed.
Your assistance in answering the above will be greatly appreciated.
Praise be to Allah.Firstly: 
The scholars differed on the ruling on one who neglects the prayer out of heedlessness and laziness. The correct view is that he is a kaafir. This has been discussed previously in the answers to questions no. 2182 and 5208. 
Once it is established that the one who does not pray is a kaafir, it is not permissible to give charity, fast and do Hajj on his behalf. 
The scholars of the Standing Committee (9/69) were asked: Is it acceptable to pray for forgiveness and give charity for one who died when he did not pray, or he used to pray sometimes and sometimes he did not pray? Is it permissible to attend his funeral and bury him in the Muslim graveyard? 
They replied: The one who does not pray because he denies that it is obligatory is a kaafir according to the consensus of the Muslims. The one who does not pray out of heedlessness and laziness is a kaafir according to the more correct of the two scholarly opinions. 
Based on that, if a person who deliberately does not pray dies, it is not permissible to pray for forgiveness for him, or to give charity on his behalf, or to attend his funeral, or bury him in the Muslim graveyard, because the Prophet (blessings and peace of Allah be upon him) said: “The covenant that stands between us and them is the prayer; whoever abandons it is a kaafir.” Narrated by Ahmad and the authors of as-Sunan with a saheeh isnaad. And he (blessings and peace of Allah be upon him) said: “Between a man and kufr and shirk there stands his giving up prayer.” Narrated by Muslim in his Saheeh. 
Standing Committee for Academic Research and Issuing Fatwas 
Shaykh ‘Abd al-‘Azeez ibn ‘Abdullah ibn Baaz … Shaykh ‘Abd ar-Razzaaq ‘Afeefi… Shaykh ‘Abdullah ibn Ghadyaan… Shaykh ‘Abdullah ibn Qa‘ood 
If your father was unaware that prayer is obligatory, or he followed scholars who ruled that the one who does not pray out of heedlessness is not a kaafir, then we hope that Allah will forgive him, and in this case supplication and prayers for forgiveness for him, and giving charity on his behalf, will benefit him. 
And Allah knows best.