The Unisonic 840-E is an arithmetic calculator with algebraic logic. It has 7 functions, and a VFD (vacuum fluorescent) display. The power source is 4xAAA.
Facts at a glance:
If you have a Unisonic 840-E that is no longer working, you can first try replacing the 4xAAA batteries. If that doesn't solve the problem, then you can consider replacing the calculator with a modern equivalent.
We suggest the following current models as possible replacements: