2r^2 interpreted as 2^2 [closed]

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Please check the types in the following code:

print("Before var:",type(r))
var('r')
print("After var:",type(r))
print("2r^2:",2r^2)
print("type(2r):",type(2r))
print("type(2*r):",type(2*r))
print("2*r^2:",2*r^2)
print("(2*r)^2",(2*r)^2)

to multiply, you need *

Duplicate of https://ask.sagemath.org/question/75093/

I found the fact that 2r^2 was accepted extremely intriguing, and queried for it. John Palmieri's insightful answer pointed me to a feature of the preparser that I ignored after years of using Sage...