Adding with the Base Ten System

http://www.vectorstock.com/royalty-free-vector/rainbow-background-vector-580934

http://www.vectorstock.com/royalty-free-vector/set-of-cartoon-number-vector-472670

Can you think of a number that doesn't use the digits 

0, 1, 2, 3, 4, 5, 6, 7, 8, or 9 in it?

EVERY number is made up of the same 10 digits

http://www.vectorstock.com/royalty-free-vector/set-of-cartoon-number-vector-472670

643 43643 43643 is bigger than 43 because it has more

digits in the number

We can break the number up by each digit's value, called Place Value

http://www.coolmath.com/prealgebra/02-decimals/01-decimals-place-value-01.htm

Every number is broken down into places:

The more digits a number has, the bigger the number is.

http://www.coolmath.com/prealgebra/02-decimals/01-decimals-place-value-01.htm

When we add numbers we need to line up them by place value.

Becomes....

The tens are lined up with the tens 

The ones are lined up with the ones

http://www.coolmath4kids.com/addition/05-addition-lesson-two-digit-numbers-01.html

Sometimes, before we add, it helps to think of our base ten blocks.

http://www.innovativeed.com/baseten.htm

How can you make 28 with base ten blocks?

How can you make 39 with base ten blocks?

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First combine all of the similar sized manipulatives (ones with ones, tens and tens, etc)

ALWAYS start with the ONES cubes and work your way up to the tens,

hundreds, thousands, etc.

17  ones becomes one 10 and 7 ones

=

5 tens is 50

So then we ADD our 5 tens and our one 10 and seven 1s

+

It becomes 6 tens and 7 ones, which is the same as67

How can we add two double-digit numbers without math blocks?

The first thing you want to do is line up your digits, ones on top of ones, tens on top of tens, etc. 

http://www.coolmath4kids.com/addition/05-addition-lesson-two-digit-numbers-01.html

Once the numbers are lined up, you start with adding the ones, just like before.

http://www.coolmath4kids.com/addition/05-addition-lesson-two-digit-numbers-01.html

http://www.coolmath4kids.com/addition/05-addition-lesson-two-digit-numbers-01.html

Then we add our tens digits together and we get......

The same answer as before!http://www.coolmath4kids.com/addition/05-addition-lesson-two-digit-numbers-01.html

Now let's practice adding double-digit numbers 

using both ways!