Ask Hackaday: Do We Need a 21st Century Calculator?

The HP-41C analog on my phone gives the right answer. Three resistors in parallel: 4.7 k,Ω 22 kΩ, and 3.3 kΩ. You can estimate it, of course, but if you want the actual 1.8 kΩ (approximately) answer, you probably reached for some kind of calculating aid.