Adding and Subtracting

Place Value with Adding, Subtracting, Rounding

by Maria Almanza

​Place Value Chart

​Place value always moves right to left.

​

​"To the left, to the left. Start on the right

and move to the left."

​<----------------------------- *Start here

​

​This is important for adding, subtracting,

​and rounding.

​Adding

• ​Where do we start?

  • ​The Ones (1's)

  • ​Then the Tens (10's)

  • ​Then the Hundreds (100's)

  • ​Lastly, Thousands (1,000's)

  • ​

  • ​When do we regroup?

  • ​When the sum is 10 or greater!

Subtracting

• ​Where do we start?

  • ​The Ones (1's)

  • ​Then the Tens (10's)

  • ​Then the Hundreds (100's)

  • ​Lastly, Thousands (1,000's)

  • When do we borrow?

  • ​When the number on top is smaller than the number on bottom!

  • ​Who do we borrow from?

  • ​The neighbor to the left!

​Rounding

• ​Where do we start?

  • ​Find the number in the place value that is being rounded.

  • ​Find the neighbor to the right --------------->

  • ​5 or more, round up one digit.

  • ​4 or less, leave the place value the same.

  • ​Everything after, gets a zero.

Poll

What is the correct answer?

• 471

• 571

• 561

• 581

Poll

What is 61 take away 24? 

61

-24 

______________

• 37

• 42

• 33

• 51

Poll

Round to the nearest ten and nearest hundred.

• 540

  600

• 550

  600

• 550

  500

• 540

  500