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## Early math review

### Unit 5: Lesson 4

Intro to addition with 2-digit numbers

# Breaking apart 2-digit addition problems

## Want to join the conversation?

• how do you break apart three digit numbers?
• To break apart 3 digit numbers, you separate the hundreds digit, the tens digit, and the ones digit. For example, if you were trying to break apart 729, you will separate the hundreds digit, which is 7, the tens digit, which is 2, and the ones digit, which is 9. So, 729 = 700 + 20 + 9.
(1 vote)
• I still don't get it.
• I'll explain the steps

Let's do 83 + 11.

83 is 80 + 3
11 is 10 + 1

now it's 80 + 3 + 10 + 1
we can first add 80 + 10 which is 90
then add 3 + 1 which is 4

now we just add 90 + 4 which is 94

there, the answer to 83 + 11 is 94.
• what do you broke up ()
• He is saying that in the options, the numbers are represented as tens and ones, instead of a normal number. For example, in this case, the 41 is represented as 4 tens and 1 one; but a different way to broke up the numbers is to represent them as a normal number, so that would be 40 + 1.
• how do you break apart a 2-digit number
• we break it into ones and tens. For example 21=2*10+1*1 (21 is two tens plus 1)
• how do you break apart four digit number
• By break apart, do you mean switch to standard form? If so, lets imagine the number is 4,878

First, the last digit is the ones place. So, the 8 in the last digit is only equal to 8.

Second, the second to last digit is the tens. So, that is equal to 70.

Next, the third to last digit is the hundreds. So, the 8 there is equal to 800.

And finally, the first number is in the thousands. So the
• How do you break apart 6 digit number?
• Like you'd break apart any other number!
For example,
283,729
200,000 + 80,000 + 3,000 + 700 + 20 + 9
• how do you add 39 + 61
• Well, try breaking it up.
30+60, and 9+1
30+60 is 90, because 3+6 is 9. And 9+1 is 10!! Meaning, 90+10 is 100, so your answer is 100.
• How can we do (Breaking apart 2-digit subtraction problems)
I did not understand this thing. 'Breaking apart 2-digit addition problems' is very clear to me. :)
• When introducing 2 digit subtraction without regrouping, I always start with the base ten models. In addition to using base ten blocks, I also teach them to draw the blocks out on paper. This is because students won’t always have access to manipulatives, but they will have a pencil and paper. I always give my students a place value mat placed inside a plastic sleeve. This allows students to also write or draw using a dry erase marker and they can be used over and over again. Here is how this strategy works using the example 59-15=44

Build/draw out the minuend (59) with base ten blocks.
Take away the amount of the subtrahend (15). Remove 5 ones blocks and 1 tens block.
Count the remaining blocks left and solve for the difference.