When Newton died, the British started the new year on March 25 (Lady Day). In 1752, the UK switched to starting the New Year on January 1. Dates between January 1 and March 25 prior to 1752 happened in different years Old Style vs. New Style.

This is all explained nicely at https://en.wikipedia.org/wiki/Old_Style_and_New_Style_dates

Added (thanks to @LangLangC for the excellent link): https://thonyc.wordpress.com/2015/03/20/calendrical-confusion-or-just-when-did-newton-die/

When Newton died, the British started the new year on March 25 (Lady Day). In 1752, the UK switched to starting the New Year on January 1. Dates between January 1 and March 25 prior to 1752 happened in different years Old Style vs. New Style.

This is all explained nicely at: Wikipedia: Old Style and New Style dates

Added (thanks to @LangLangC for the excellent link): Calendrical confusion or just when did Newton die?

When Newton died, the British started the new year on March 25 (Lady Day). In 1752, the UK switched to starting the New Year on January 1. Dates between January 1 and March 25 prior to 1752 happened in different years Old Style vs. New Style.

This is all explained nicely at https://en.wikipedia.org/wiki/Old_Style_and_New_Style_dates

When Newton died, the British started the new year on March 25 (Lady Day). In 1752, the UK switched to starting the New Year on January 1. Dates between January 1 and March 25 prior to 1752 happened in different years Old Style vs. New Style.

This is all explained nicely at https://en.wikipedia.org/wiki/Old_Style_and_New_Style_dates

Added (thanks to @LangLangC for the excellent link): https://thonyc.wordpress.com/2015/03/20/calendrical-confusion-or-just-when-did-newton-die/