The year 2021 is the 170th year of FSU (170 = 2021 - 1851) and I arrived in its 117th year which gives me 53 = 170 - 117 years at FSU
Am I that old? ... No.
Did I arrive as a teenager? ... No.
What happened?
The baseline changed in March 2000, FSU changed its origin date from 1857 (when the first classes began), to 1851 (when the legislation creating the school was enacted). Hence 117 = 1974 - 1857.
Erd\"os claimed to be 2.5 billion years old because the age of the Earth jumped from 2 billion to 4.5 billion.