The plaid table runner is complete. It's imperfect, and needs ironing, but I'm still pretty happy with how it turned out. #weaving
I put a piece of masking tape on my loom and wrote down the Forbes Tartan thread count so I could keep track. This project will require three complete passes.
Now the scarf is off the loom and I just finished the edges. Now it just needs a hand wash and it will be done. #weaving
Making progress on the scarf. This pattern calls for sparse spacing in the weft (6ppi) with a finer yarn and it's weird seeing these gaps. Apparently it all fills in when off the loom and washed. #weaving
Multiplication is repeated addition, shifting left for each digit in the multiplier. Here is 12 x 12. Because of the extended complements for subtraction method, division is possible but not ideal.
To clear the register, you turn the knob on the bottom right side anti-clockwise until all the digits say 0.
The chain only moves in one direction, so to subtract you have to use the complements method. To subtract 42 from 31342, I add 9999958.
These are portable, but are bigger and heavier than other pocket calculators of the time and primarily sat in or on a desk using the kickstand, and were used for quick arithmetic. To add a number, insert a stylus at the corresponding digit and drag down to the bottom.
These are known as chain adders. By inserting a stylus and dragging the chain down, you increment the register. You can see the carry mechanism in this video, which uses a spring-loaded tooth that rides along the outside of the gear and engages with the next gear only after 9.
Division aside though, this is my favorite lever style adding machine in my collection to use, due to the subtraction key and overall key placement that enables one-handed operation. I could actually see myself using this to balance a checkbook if I still did that sort of thing.
Multiplication is repeated addition, shifting left for each digit in the multiplier, like other lever adding machines. By pressing down the repeat key the keys stay depressed after you pull the lever so you press the Correction key to release them and shift left. Here is 12 x 12.
Technical author, FOSS advocate, public speaker, Linux security & infrastructure geek, author of The Best of Hack and /: Linux Admin Crash Course, Linux Hardening in Hostile Networks and many other books, ex-Linux Journal columnist.