10-digit calculator with a protective wallet case features 44 built-in, metric conversion functions to help you make quick, simple calculations. Easy-to-read, extra-large LCD showcases sharply defined numbers to help prevent reading errors. Conversion keys are colored in a different shade for simple operation. Rubber keys are durable to withstand daily wear-and-tear and fading for lasting performance. Twin-power operation runs on solar energy with a battery backup to deliver consistent, reliable use in any environment. Handheld calculator also includes change sign, percent, square root keys, three-key independent memory, and more.