We haven’t used a hand calculator in a very long time, but if we did we would surely choose one of Canon’s eco-friendly line, with upper and lower casings made of 100% recycled plastic from Canon Copiers. Each is lightweight and has a large liquid crystal display and runs on lithium coin mercury-free batteries and/or solar power. Choose between the LS-154TG for $10.99, the HS-1000TG at $15.99 or the TS-1200TG with a price of $19.99.