Windows calculator is wrong with maths

It depends on the mode.

Standard will give you 49, the others 37.

A scientific calculator semi-officially was a floating point calculator, but the windows one had at least some capabilities beyond that, although I forgot which one exactly.

Perhaps the standard mode is working like a classical calculator that would also report 49 and perhaps it is just a reskin of the original one that makes everything worse, because it actually prints: 2+5*7 = 49 which does not imply calculations are done in order of input.