An adding machine is also called a 10-key or a printing calculator. They no longer teach students how to use these machines, but they still use them in companies. Adding machines have a lot of symbols and buttons. Some are foreign and strange to anyone who has never used an adding machine, but it isn't very difficult to learn how to use an adding machine as long as you follow the directions. Most adding machines are the same, but may have different symbols. If you can't find a certain symbol, look for a similar one.

Add and subtract on the adding machine by pressing each number followed by its mathematical sign. For example, press the "6," "+," "7," "+," "-4" and "=" buttons for the equation "6 + 7 + (-4) = 9."

Multiply and divide by pressing a number followed by the sign and then the next number. For example, press "6," "x," "6" and "=" for the mathematical equation "6 x 6 = 36."

Press the "Up" arrow on the adding machine to advance the paper up without printing. The arrow pointing to the right removes the last digit entered.

Choose the "M+" button to save the currently displayed value into the adding machine memory. An "M" will display on the screen. If you press it again, it will add the new amount to the existing memory. If you want to subtract the currently displayed value from the memory, press the "M-."

Press the "M" with a diamond shape next to it to print the value stored in the memory without erasing it. The "M*" button will print the stored memory and clear it.

Clear every operation in progress by pressing the "C" key. This will not erase any stored memory. The "CE" key will clear the screen, but will not clear any operations in progress.

Display and print the subtotal by pressing the diamond key. The adding machine will remember the total for the following entry. Press the "*" key to print the current total and set the machine back to zero.

Things You Will Need
  • Adding machine

  • Paper


Companies that still use an adding machine sometimes require employees to know how to use the machine without looking, the same as typing on a typewriter. There are classes offered for learning how to use the 10-key.


It is important that you follow the directions carefully to ensure that your totals are correct.