1. Look at the speed
The calculation speed of the calculator must be fast. It is also necessary to ensure that the number cannot be wrong.
2. Flexible buttons
The calculator must be pressed to get the number, otherwise it will be very troublesome.
3. The screen is clear and there is no trace
The calculator must have a clear screen and no traces. Here is a method: 1. Press the number 8 continuously to check whether the number is complete. 2. Check whether the decimal point can be displayed (check every digit).
4. Is the outer cover damaged?
If it is damaged, do not buy it, it is likely that the electronic parts will fall off and damage the calculator.