It is an easy-to-use calculator that always displays the value of the memory. Also, since the calculation formula is displayed, you can check the input contents. Calculation results can be registered in a database, sent by e-mail, or entered in a memo pad.1. The calculator can calculate addition, subtraction, multiplication and division, square root, exponentiation, reciprocal, pi, tax excluded, and tax included. Calculation results can be stored in memory and used. Since the memory value is always displayed, there is no need to read and check it. In addition, since the entered value and calculation formula are displayed, you can calculate while checking.Calculation results, formulas, and calculation dates can be registered in the database for later use. It is easy to understand if you give it a name when registering the database. Also, if you touch {Mail}, you can immediately send the calculation result, calculation formula, calculation date and time by e-mail, or write it in the memo pad.2. Settings set the tax rate and key touch sound. Touch sounds can be selected from none, animal or bird sounds. Touch [Set] to register in the database.3. The registration list is a list of names, values (calculation results), formulas (calculation formulas), and dates (calculation dates) registered in the database. You can sort by name, value, date/time in ascending or descending order. If you touch the name or value and then touch [Show on display], the value will be displayed on the calculator display. Touch Show in Memory to store the value in the calculators memory.By touching [Send Mail], you can send the name, calculation result, calculation formula, calculation date and time by e-mail, or write it in the memo pad.4. How to use is an explanation of the buttons in the app. Touch the button to display the explanation.