How to calculate a multiplication

Multiplication is one of the fundamental mathematical operations. It's a short way of adding numbers several times. For example, when you multiply 13 times 5, the number 13 is added five times. To illustrate how multiplication works, let's multiply the number 4 by 5 and 4 by 0. The multiplication calculation requires an understanding of how to add numbers and what happens when you add a number zero times.

You will need to:
  • Calculator
Steps to follow:


Write the first number in the problem of multiplication by the amount that appears in the second number in the problem. In our example, if we are multiplying 4 x 5, then we can write the number 4 five times. We do this because we are literally adding the number 4 a total of five times.


Add the numbers you have written that in our case, let's add 4 + 4 + 4 + 4 + 4. These numbers add up to give 20, which is the correct answer. If you have difficulty adding the numbers, add two of them and then add the number next to your answer. For example, add 4 + 4 = 8 and then add 4 + 8 = 12 and so on until the number is added five times.


Verify your answer by comparing the answer to a multiplication table or a calculator . A multiplication table is a graph that shows the answer when one number is multiplied by another. You see a column at the top that says "4" and drag your finger until it intersects with another column that says "5", to see that the answer is 20.


Another example could be 3 x 7, we can add 3 seven times as well as add 7 three times.

  • 3 + 3 + 3 + 3 + 3 + 3 + 3 = 21
  • 7 + 7 + 7 = 21
  • Multiplication has a property called commutative property. This means that the response to 4 x 5 is the same as the response to 5 x 4.
  • Set the response to zero for 4 x 0. Each number multiplied by zero is always equal to zero. This is because a number added zero times is not added, and is equal to nothing.
  • Treat negative numbers in the same way as positive numbers, with one exception - two negative numbers multiplied by themselves are always equal to a positive number. To modify the example above, -4 x -5 = 20. This is because we add a negative number
  • Put a negative sign in front of the answer if you multiply a positive number by a negative number. In our example, -4 x 5 = -20. Unlike the multiplication of two negatives, the addition of a positive in a negative amount of time always results in the negative number.