enter it into any calculator and you should get 9

Have you tried it, though? My Casio says it’s 1

That’s because it treats 2(1+2) as 2x and not 2*x

That’s called juxtaposition and is the reason why people find this notation ambiguous. Some people account for it, some not. Same with calculators. The scientific ones are most likely to give you an answer of 1