Multiplying any number by zero always equals zero. Below are some examples.

  • 5 \times 0 = 0

  • 123\times 0 = 0

  • -314\,159 \times 0 = 0

  • 0\times 0 = 0

To see why multiplying any number by zero always equals zero, let's take a look at the multiplication table for 5 , shown below.

\begin{align*} 5\times{\color{red}{4}} &= {\color{blue}{20}}\\ 5\times{\color{red}{3}} &= {\color{blue}{15}}\\ 5\times{\color{red}{2}} &= {\color{blue}{10}}\\ 5\times{\color{red}{1}} &= {\color{blue}{5}}\\ 5\times{\color{red}{0}} &= {\color{blue}{\square}}\,? \end{align*}

As we go down the list, the number in blue is reduced by 5 each time. Following this pattern, we must have \color{blue}\square = 0 .

Note that, since multiplication is commutative, multiplying zero by any number (including itself) equals zero as well. Some examples are shown below.

  • 0 \times 5 = 0

  • 0 \times 123 = 0

  • 0 \times -314\,159 = 0

  • 0 \times 0 = 0

FLAG

What is the value of 3 \cdot 0?

EXPLANATION

Multiplying any number by zero always gives zero. Therefore, 3 \cdot 0 = 0.

FLAG

Calculate the value of $1\,255 \cdot 0.$

a
$-1\,255$
b
$0$
c
$125$
d
$1\,255$
e
$\dfrac{1}{125}$

Calculate the value of $15 \cdot 0.$

a
$15$
b
$-15$
c
$0$
d
$150$
e
$\dfrac{1}{5}$

Dividing zero by any number (other than zero) always equals zero. For example:

  • 0 \div 2 = 0

  • 0\div (-456) = 0

To understand why dividing zero by any number (other than zero) always equals zero, think about it this way: if you have zero pizzas, and you want to divide zero pizzas among ten friends, then each friend will get exactly zero pizza.

FLAG

Calculate the value of 0 \div 5.

EXPLANATION

Zero divided by any number (other than zero) equals zero. Therefore, 0 \div 5 = 0.

FLAG

$0\div16=$

a
$0$
b
$-16$
c
$\dfrac{1}{16}$
d
$16$
e
$\dfrac{1}{6}$

$0\div5=$

a
$0$
b
$\dfrac{1}{5}$
c
$-5$
d
$5$
e
$-\dfrac{1}{5}$

Compute the value of 0 \div \left(-\dfrac 1 2\right).

EXPLANATION

Zero divided by any number (other than zero) equals zero. Therefore, 0 \div \left(-\dfrac 1 2\right) = 0.

FLAG

Calculate the value of $0\div\dfrac{3}{4}.$

a
$\dfrac{4}{3}$
b
Undefined
c
$-\dfrac{3}{4}$
d
$0$
e
$4$

Compute the value of $0\div\dfrac{3}{5}.$

a
$3.5$
b
$0$
c
Undefined
d
$-\dfrac{3}{5}$
e
$\dfrac{5}{3}$

Division by zero is undefined. No number can be divided by zero, not even zero itself.

To see why, notice that if we divide 6 by 3, we get

6\div 3 = 2. Therefore, by the relationship between multiplication and division, we have

6 = 3\times 2.

However, this argument does not work if we divide by zero. Suppose we have

6\div 0 = \fbox{[math]\,?\,[/math]}\,.

Then, by the relationship between multiplication and division, we have

6 = 0\times \fbox{[math]\,?\,[/math]}\,.

and this relationship cannot be true because any number multiplied by zero is zero! Therefore, \fbox{[math]\,?\,[/math]} is not a number.

FLAG

What is -2 \div 0?

EXPLANATION

We cannot divide any number by zero. Therefore, -2 \div 0 is undefined.

FLAG

$45\div0=$

a
$-\dfrac{1}{45}$
b
$\dfrac{0}{45}$
c
Undefined
d
$45$
e
$0$

What is $1\div0?$

a
$1$
b
Undefined
c
$-1$
d
$\dfrac{0}{1}$
e
$0$
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