Different answers from Solve app and solve.SOLVE - latter is "wrong"

[DavZell]

I was browsing the calculator subreddit and someone posted an equation that their Casio couldn't solve despite it being simple. I decided to check the Prime.

Please note that I'm going through a calculator binge right now, as my trusty 48SX screen just died after 35+ years. I got a 48gII and 50g (eBay), and a Prime G2 (new). So my testing this was purely to play around different ways. Boy, were not in 48sx-land any more. The 50g got this correct, too, by the way.

The equation is: 300×10^-3 = ((6.625×10^-34 × 3×10^8) × X) ÷ 6625×10^-10

The correct answer is 10^18.

Solve.SOLVE(eqn,x) yeilds 9.99999999998E17
The Solve app yeilds 1E18

The HP 50g NUM.SLV yeilds 1000000000000000000 (1E18)

It seems odd that the first solution is off considering the only division is in numbers resulting in a power of 10.

Any thoughts?