My professor taught me the simplest method of subtracting something with these 128 64 32 16 8 4 2 0 And if it is > you add 1 if less 0 I just can't recall it. More on reddit.com

Ah yes, I have no idea what’s going on. More on reddit.com

I would have thought many scientific calculators could do this, but not the graphing calculators that would have more extensive memory features. For example, all of these have keys for BIN/HEX/OCT/DEC. It says 'operating system calculators' -- I wonder if this means the scientific & programming calculators typically included with Windows, Linux, etc. because these can generally do BIN/HEX/DEC conversions with features similar to basic dedicated scientific calculators. When they say 'memory' I don't think they're referring to the typical ability to store one or two values (M+/MR), they don't want you having extensive notes or programs. They're vintage and semi-collectible at this point but the Casio CM-100 'computer math calc' has these keys unshifted as does HP-16C. More on reddit.com

It can convert 6 digit numbers to binary. Here you can see it converted 999.999 to binary (max input). Output is 20 bit (last bit is useles rigth now) One module of it has a valume of 98.280 m3. The decoder on the left (light blue part) is not included. Here i made 2 modules. So it's 196.560 m3 . It's huge. It's working with a simple logic. When you write 128 you press 1 2 8 The design captures that and convert them to binary. For example, first you press 1 and it converts to 0001. After you press 2 the 1 shifts to the front. So those numbers is written as 0001010 0010. And finally when you press 8, 1 and 2 shiftes to the front and they become 1100100 10100 1000. After converting them into those numbers it add them together. It's write them like 100+20+8=128. 1100100+10100+1000=10000000 this is our answer. More on reddit.com