Basic Math Examples

$10.5 \cdot 20$

Step 1

Multiply using long multiplication.

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Step 1.1

Multiply

$0$ by

$5$ . Place the result in the next column in the result line. There is one result line for each digit in

$20$ .


	$1$	$0$	. $5$
$⨯$		$2$	$0$
			$0$

Step 1.2

Multiply

$0$ by

$0$ . Place the result in the next column in the result line. There is one result line for each digit in

$20$ .


	$1$	$0$	. $5$
$⨯$		$2$	$0$
		$0$	$0$

Step 1.3

Multiply

$0$ by

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

$20$ .


	$1$	$0$	. $5$
$⨯$		$2$	$0$
	$0$	$0$	$0$

Step 1.4

Multiply

$2$ by

$5$ . Place the ones digit

$(0)$ in the result line and carry the tens digit

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

$20$ .

		$1$
	$1$	$0$	. $5$
$⨯$		$2$	$0$
	$0$	$0$	$0$
		$0$

Step 1.5

Multiply

$2$ by

$0$ and add the carried

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

$20$ .

		$1$
	$1$	$0$	. $5$
$⨯$		$2$	$0$
	$0$	$0$	$0$
	$1$	$0$

Step 1.6

Multiply

$2$ by

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

$20$ .


	$1$	$0$	. $5$
$⨯$		$2$	$0$
	$0$	$0$	$0$
$2$	$1$	$0$

Step 1.7

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

$0 + 0$ , then place the

$0$ in the result line.


	$1$	$0$	. $5$
$⨯$		$2$	$0$
	$0$	$0$	$0$
$2$	$1$	$0$
			$0$

Step 1.8

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

$0 + 0$ , then place the

$0$ in the result line.


	$1$	$0$	. $5$
$⨯$		$2$	$0$
	$0$	$0$	$0$
$2$	$1$	$0$
		$0$	$0$

Step 1.9

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

$0 + 1$ , then place the

$1$ in the result line.


	$1$	$0$	. $5$
$⨯$		$2$	$0$
	$0$	$0$	$0$
$2$	$1$	$0$
	$1$	$0$	$0$

Step 1.10

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

$0 + 2$ , then place the

$2$ in the result line.


	$1$	$0$	. $5$
$⨯$		$2$	$0$
	$0$	$0$	$0$
$2$	$1$	$0$
$2$	$1$	$0$	$0$


	$1$	$0$	. $5$
$⨯$		$2$	$0$
	$0$	$0$	$0$
$2$	$1$	$0$
$2$	$1$	$0$	$0$

Step 2

To find the number of decimal places needed in the answer, add the number of decimal places in the multiplier and multiplicand. In this case, there is a total of

$1$ , so the answer must have

$1$ decimal places as well.

$210$