Ms Das handed over 91kg (200lb) of coins - the produce of 44 years of hard begging - enabling her to open an account and qualify for a credit card.
Laxmi began begging near Hatibagan, a busy road junction in northern Calcutta, at the age of 16.
Officials say she could have saved as much as 30,000 rupees ($692).
"She would spend frugally from her daily collection and save the coins. She was very possessive about them," says her sister Asha.
Ms Das saved the coins in iron buckets covered with jute bags at her home in a shanty town near the crossing.
In all, she collected four buckets of coins - of all denominations - some even minted as far back as 1961 and now clearly out of date.
"But we will accept those coins as well because she is poor and needs all our support," said Central Bank of India spokesman Shantanu Neogy.
He says there is a directive from India's Reserve Bank to accept all such outdated coins and reimburse the depositor in full.
Ms Das told bank officials that she had stored the coins for when she reached "old age" and needed a pension plan for when she was too old to beg.
Old Indian coins fetch high prices in Bangladesh (Photo: Subhamoy Bhattacharjee)
She was encouraged to deposit the money by police who feared it could have been stolen from her home.
"It is not safe for her to have the coins in the shanty any more, now that people have come to know," said police officer Baidyanath Saha. "A bank account would be the best option for her unique savings."
Bank officials say they are still counting thousands of her coins and still do not know the exact amount.
They say that there are "a lot of coins to count".
Once her account is eventually opened, officials at the Central Bank of India will give her advice on how to use her money.
Ms Das chose to ignore - or did not know about - a thriving racket in this part of the world in which old Indian coins are smuggled and melted down in Bangladesh to make razor blades that sell for up to seven times their value as coins.The scam has caused an acute coin shortage in eastern India, forcing government mints to cut down on the amount of metal they now use to make the coins.
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