For me, I think it’s pretty close for the numbers that are right on, and multiplying is way easier for intermediate numbers. 50->80 is one beat in my brain, it

For me, I think it’s pretty close for the numbers that are right on, and multiplying is way easier for intermediate numbers. 50->80 is one beat in my brain, it’s basically immediate because I know the first many Fibonacci numbers. But multiplying by 1.6 is only two beats, it’s “add a half” and then “add a tenth”, each of which come just as automatically as recalling a two Fibonacci numbers. 50->75->80. For the in-between numbers, 1.6 seems way easier. 40->60->64 is much quicker for me than averaging 50 and 80.