Common core subtraction

Common core subtraction - counting up method of subtraction

Common core subtraction is using addition instead. Add up from the smaller number to the bigger number.

Subtraction = Addition

To subtract using the common core we use the same method as addition but the other way around

Yes Really! Subtraction is addition.

Example 1

$32-12$

$12$	$+$	$3$	$=$	$15$
$15$	$+$	$5$	$=$	$20$
$20$	$+$	$10$	$=$	$30$
$30$	$+$	$2$	$=$	$32$

		$20$

To see this step by step

Answer: $32-12=20$

Example 2

$43-13$

$13$	$+$	$2$	$=$	$15$
$15$	$+$	$5$	$=$	$20$
$20$	$+$	$10$	$=$	$30$
$30$	$+$	$10$	$=$	$40$
$40$	$+$	$3$	$=$	$43$

		$30$

To see this step by step

Common core subtraction step by step

Example 2

$43-13$


	$13$					Start with the lowest number


	$13$	$+$	$2$			Add $2$ because it's then easy to get to $15$


	$13$	$+$	$2$	$=15$		$15$ is the running total


	$13$	$+$	$2$	$=15$		Put the running total on the next line
	$15$


	$13$	$+$	$2$	$=15$		Add $5$ because it's then easy to get to $20$
	$15$	$+$	$5$


	$13$	$+$	$2$	$=15$		$20$ is the running total
	$15$	$+$	$5$	$=20$


	$13$	$+$	$2$	$=15$
	$15$	$+$	$5$	$=20$
	$20$					Put the running total on the next line


	$13$	$+$	$2$	$=15$
	$15$	$+$	$5$	$=20$
	$20$	$+$	$10$			Add $10$ because it's then easy to get to $30$


	$13$	$+$	$2$	$=15$
	$15$	$+$	$5$	$=20$
	$20$	$+$	$10$	$=30$		$30$ is the running total


	$13$	$+$	$2$	$=15$
	$15$	$+$	$5$	$=20$
	$20$	$+$	$10$	$=30$
	$30$	$+$	$10$			Add $10$ because it's then easy to get to $40$


	$13$	$+$	$2$	$=15$
	$15$	$+$	$5$	$=20$
	$20$	$+$	$10$	$=30$
	$30$	$+$	$10$	$=40$		$40$ is the running total


	$13$	$+$	$2$	$=15$
	$15$	$+$	$5$	$=20$
	$20$	$+$	$10$	$=30$
	$30$	$+$	$10$	$=40$
	$40$					Put the running total on the next line


	$13$	$+$	$2$	$=15$
	$15$	$+$	$5$	$=20$
	$20$	$+$	$10$	$=30$
	$30$	$+$	$10$	$=40$
	$40$	$+$	$3$			Add $3$ to finally get $43$


	$13$	$+$	$2$	$=15$
	$15$	$+$	$5$	$=20$
	$20$	$+$	$10$	$=30$
	$30$	$+$	$10$	$=40$
	$40$	$+$	$3$	$=43$		Check the final equals $43$


		$+$	$2$
		$+$	$5$
		$+$	$10$
		$+$	$10$
		$+$	$3$			Now add

			$30$

Answer: $43-13=30$

Answer: $43-13=30$

Example 3

$325-38$

$38$	$+$	$2$	$=$	$40$
$40$	$+$	$60$	$=$	$100$
$100$	$+$	$200$	$=$	$300$
$300$	$+$	$25$	$=$	$325$

		$287$

To see this step by step

Answer: $325-38=287$

Example 4

$264-128$

$128$	$+$	$2$	$=$	$130$
$130$	$+$	$70$	$=$	$200$
$200$	$+$	$60$	$=$	$260$
$260$	$+$	$4$	$=$	$264$

		$136$

To see this step by step

Answer: $264-128=136$

OR

$128$	$+$	$100$	$=$	$228$
$228$	$+$	$30$	$=$	$258$
$258$	$+$	$2$	$=$	$260$
$260$	$+$	$4$	$=$	$264$

		$136$

Answer: $264-128=136$