Basic Math Examples

21 \cdot 19

$21 \cdot 19$

Step 1

Multiply using long multiplication.

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Step 1.1

Multiply

9

$9$ by

1

$1$ . Place the result in the next column in the result line. There is one result line for each digit in

19

$19$ .


	$2$ $2$	$1$ $1$
$\times$ $⨯$	$1$ $1$	$9$ $9$
		$9$ $9$

Step 1.2

Multiply

9

$9$ by

2

$2$ . Place the ones digit

(8)

$(8)$ in the result line and carry the tens digit

(1)

$(1)$ . There is one result line for each digit in

19

$19$ .


	$2$ $2$	$1$ $1$
$\times$ $⨯$	$1$ $1$	$9$ $9$
$1$ $1$	$8$ $8$	$9$ $9$

Step 1.3

Multiply

1

$1$ by

1

$1$ . Place the result in the next column in the result line. There is one result line for each digit in

19

$19$ .


	$2$ $2$	$1$ $1$
$\times$ $⨯$	$1$ $1$	$9$ $9$
$1$ $1$	$8$ $8$	$9$ $9$
	$1$ $1$

Step 1.4

Multiply

1

$1$ by

2

$2$ . Place the result in the next column in the result line. There is one result line for each digit in

19

$19$ .


	$2$ $2$	$1$ $1$
$\times$ $⨯$	$1$ $1$	$9$ $9$
$1$ $1$	$8$ $8$	$9$ $9$
$2$ $2$	$1$ $1$

Step 1.5

Add the numbers in each column. In this case, add

9 + 0

$9 + 0$ , then place the

9

$9$ in the result line.


	$2$ $2$	$1$ $1$
$\times$ $⨯$	$1$ $1$	$9$ $9$
$1$ $1$	$8$ $8$	$9$ $9$
$2$ $2$	$1$ $1$
		$9$ $9$

Step 1.6

Add the numbers in each column. In this case, add

8 + 1

$8 + 1$ , then place the

9

$9$ in the result line.


	$2$ $2$	$1$ $1$
$\times$ $⨯$	$1$ $1$	$9$ $9$
$1$ $1$	$8$ $8$	$9$ $9$
$2$ $2$	$1$ $1$
	$9$ $9$	$9$ $9$

Step 1.7

Add the numbers in each column. In this case, add

1 + 2

$1 + 2$ , then place the

3

$3$ in the result line.


	$2$ $2$	$1$ $1$
$\times$ $⨯$	$1$ $1$	$9$ $9$
$1$ $1$	$8$ $8$	$9$ $9$
$2$ $2$	$1$ $1$
$3$ $3$	$9$ $9$	$9$ $9$


	$2$ $2$	$1$ $1$
$\times$ $⨯$	$1$ $1$	$9$ $9$
$1$ $1$	$8$ $8$	$9$ $9$
$2$ $2$	$1$ $1$
$3$ $3$	$9$ $9$	$9$ $9$

Step 2

The result of

21 \cdot 19

$21 \cdot 19$ is

399

$399$ .

399

$399$