The TI-5640 is a large, sleek desktop calculator that doesn't have some of the advanced features offered by its more expensive Texas Instruments cousins, but would still suit the needs of most businesses. We were especially impressed with the built-in printer, which is loud but fast (3.5 lines per second, to be exact) and capable of eminently readable output. The 12-digit display is also very legible thanks to its oversized digits, but it unfortunately uses a black on gray LCD that isn't backlit or otherwise illuminated. This helps keep the price down, but ultimately isn't as easy to use as the calculators we have tested that use illuminated green displays.
The feel of the keys and overall layout of the keyboard are perfectly adequate--again, not as good as the best we've used, but still very usable with a little practice. With the exception of the + key, which rocks to one side too much when struck, the keys are responsive and spaced well. Switches above the keyboard are used to choose one of seven decimal display modes (floating, five fixed modes, and an add mode), to set up rules for rounding, and to control the printing mode. A dedicated grand-total key made it easy to add up the totals from several calculations, and there's also a dedicated profit-margin key. The only thing we missed were dedicated keys for adding and subtracting tax, but given the overall quality and ease of use displayed by the TI-5640, that's more wishful thinking than a deal-breaker. If you don't have any use for the extra features some of the other calculators in this category offer and you work in conditions where the lighting is good enough without an illuminated display, the TI-5640 should meet your needs and those of most office workers. --T. Byrl Baker
Pros:
- 12-digit display
- Huge selection of decimal display modes
- Grand Total key
Cons:
- No dedicated tax keys
- Printer is fast but loud