Regroup or Not 2 Digit

when you want to add or subtract 2-digit number always start with the ones digits

REmember

Multiple Choice

Subtract

• 33

• 39

• 36

• 30

Double Digit Subtraction

Review

Subtraction:

If there's more on top, you don't have to stop!

If there's more on the floor, go next door!

Multiple Choice

Which number sentence would you need to use regrouping with?

Subtraction

• Subtraction is a math operation that we use to find the difference between two numbers.

• When we subtract, we are removing one number from the other.

Subtraction Strategies

• When we are subtracting two numbers, we should always begin by estimating the difference.

• It is important to estimate first so that we can determine if our solution is reasonable.

when the sum of the ones digit is greater than 9 for example 12 we should put the tens digit which is 1 in the balloon in the tens place.

​ look at the video above

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​​Addition

​when subtracting to digit numbers,(example 92-27). the ones digit of the first number (2) less than that of the second number (7). So the ones digit (2) will ask her friend the tens digit (9) to give her a ten. the 9 will be 8 and the 2 will be 12

​ look at the video above ​

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​​Subtraction

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Multiple Choice

In what place should I start subtracting?

• hundreds

• tens

• ones

Subtraction with 2 Digit Numbers

When your doing subtraction with 2 digit numbers you must remember to always start in the One's place

Another way to remember this is that you must always do the problems from right to left

Subtraction with 2 Digit Numbers Continued

• In some or if not most Subtraction problems you will have to use Regrouping

• You have to use Regrouping when you use subtraction to find the difference between a smaller number and a bigger number

Multiple Choice

Hanna has 51 popsicles. 27 of her popsicles melt. How many popsicles does she have left?

• 78
• 24
• 36