Comptometer Arithmetic Operations

This video tutorial demonstrates how to perform basic arithmetic operations on a comptometer, including addition, subtraction, multiplication, and division. The instructor explains the importance of zeroing the register before starting and provides detailed steps for each operation. Addition is straightforward, while multiplication is achieved through repeated addition. Subtraction requires a trick involving mental arithmetic and blocking carries, and division is performed through repeated subtraction. The tutorial emphasizes the efficiency of touch typing for quick calculations.

What is the first step before starting any arithmetic operation on the comptometer?

• Turn off the machine

• Zero the register

• Select the operation mode

• Check the battery

How do you add numbers on the comptometer?

• By typing each number and pressing add

• By using the top row of buttons

• By typing all numbers in sequence

• By using a special add button

What is the result of adding numbers 1 to 19 on the comptometer?

• 220

• 210

• 200

• 190

How is multiplication performed on the comptometer?

• By typing the number twice

• By repeated addition

• By using the top row of buttons

• By using a multiplication button

What is the result of multiplying 37 by 7 on the comptometer?

• 370

• 259

• 148

• 481

Why can't subtraction be directly performed on the comptometer?

• The buttons only add

• The machine is not designed for subtraction

• There is no subtraction button

• It requires a special tool

What is the trick to perform subtraction on the comptometer?

• Adding the complement

• Using a subtraction button

• Using a calculator

• Typing the number twice

How do you handle the extra carry when subtracting on the comptometer?

• Subtract it manually

• Use metal buttons to block it

• Ignore it

• Add it to the result

What is the first step in division on the comptometer?

• Divide the numbers

• Multiply the numbers

• Add the numbers

• Subtract the divisor

How is division performed on the comptometer?

• By using a division button

• By repeated subtraction

• By repeated addition

• By typing the divisor twice