How old is George Washington's grandma?

George Washington's paternal grandmother, Mary Montague, was born in 1708 and passed away in 1789, making her 81 years old at the time of her death. His maternal grandmother, Mary Ball, was born in 1701 and died in 1761, reaching the age of 60. Given that both of these figures are historical and no longer living, they do not have an age in the present day.