Could you tell her the rail ticket number that she lost? Riddle

Lost ticket number

It was the year 1825, when the mother of Brianna, journalist of the Morning Post, set off her daughter and her siblings at the Adwick railway station. It was the cold weather, afternoon time and Christmas holidays had just ended in England so train was crowded with passengers.

When the train begun moving on railway tracks when train conductor blew whistle, Brianna happily waived good bye gesture to her mother Louisa after embarking on train from window. Brianna who was being excited to go back to her work after spending holidays with her family, amused by looking out green fields, orchards from the window suddenly an ticket collector approached and asked to show her ticket. She puzzled when she couldn't find ticket in her clutch, faced trouble and asked her siblings but they had their tickets. Seeing that situation, ticket collector insisted that she must had to show her ticket otherwise had to get off from train.

The gentleman sitting opposite to Brianna interrupted and offered his help to sort out that issue and convinced a ticket collector to tell her ticket number instead of showing ticket. He asked her siblings to tell their ticket numbers only so they told as 6,457, 7,645, and 5,764. Gentleman had an acumen, was a mathematics teacher in Irish high school by profession, told her ticket number must be 4,576. Hearing the accurate answer of her ticket number, ticket collector got surprised and allowed Brianna to travel in train.

Did you find how gentleman found out the correct answer? If yes than don't need to worry. If no, than let me tell you how he calculated the next ticket number. Let me tell you the logic behind it. If you just take last number which was 4 in the last number of 5,764, just add 4 in previous number before the first three digits, the next number would be 4,576. Got it now.