How does PICO-8 store numbers?
First stop, the manual. Here's what it says
Numbers in PICO-8 are all 16:16 fixed point. They range from -32768.0 to 32767.99
And for more detail, here's a quote from the PICO-8 Forum written by forum member musurca
In Pico-8 there are no floating-point numbers, or integers for that matter. All numbers in Pico-8 are stored as 1:15:16 fixed-point—1 bit for the sign, 15 bits for the whole number, and 16 bits for the fractional component—which means that they all take up 32 bits of space in memory. The only difference between an integer and a number with a decimal is that the integer's bits after the decimal are set to zero.
If we want to calculate pi to an impressive number of decimal points using PICO-8's native number format, how many places to the right of the decimal point can we expect? One bit in the fractional side of this format is 0x0.0001, or 1 / 0x10000, or 1 / 65536 which expressed as a base 10 decimal number is 0.00001525878. So 4 places for sure, and almost 5.