Add in Columns: Regrouping Twice

This is a complete lesson with instruction and exercises about regrouping twice in addition: both in tens and in hundreds (carrying two times), meant for 2nd or 3rd grade. First, the lesson shows with base ten blocks what happens when we need to regroup two times. Then, students do exercises using visual models while recording the sums horizontally. Then they write the addends under each other while still using the visual model. Lastly, we go to the abstract only, without a visual model. The lesson also has word problems and a puzzle problem in the end.

1. Circle ten 1-dots to make a new ten, AND circle ten 10-sticks to make a new hundred.
    Write the addition. Alternatively, you can do these exercises using base-ten blocks or similar manipulatives.

a.                         +                     __________ + ________ = __________	b.                           +                               __________ + ________ = __________
c.                   +                             __________ + ________ = __________	d.                           +                       __________ + ________ = __________

hundreds    1    tens 1  ones    1 8 7 + 1 3 8   3 2 5       Add in the ones column: 7 + 8 = 15. There are more than 10 ones, so regroup them as 1 ten 5 ones, writing “1” in the tens column. Add in the tens column: 1 + 8 + 3 = 12. There are 10 tens, so regroup them as 1 hundred, writing “1” in the hundreds column.

2. Write the numbers in the grid, and add. Regroup. You can circle 10 ten-sticks AND
    10 ones in the picture to help you. Alternatively, you can do these exercises using base-ten blocks
     or similar manipulatives.

a.                                  +                     96  +  145

b.                             +                           185  +  157

c.                                        +                 359  +  63

d.                               +                                    267  +  385

4. Add. Regroup two times if necessary.

a. 3  0  6  + 4  6  1	b. 2  9  9  + 2  2  5	c. 4  8  8  + 3  2  2	d. 1  1  5  +  5  3  6
e. 7  0  4  +   1  5  6	f. 2  6  0  +   3  4  1	g. 2  4  8  +   3  7  6	h. 1  7  3  +   6  4  6
i. 4  0  4 1  9  9 +   1  5  6	j. 7  0  1 1  2  9 +   1  0  1	k. 3  3  5 2  1  9 +   2  7  8	l. 1  0  3 2  8  0 +   5  4  7

5. Matt solved 650 + 331 in an interesting way. Can you follow his thinking? Fill in.

    First I check the hundreds: 600 + 300 makes _________.

    Then I add the _____________, and I get 50 + ______ = ______ .

    Lastly in the ones, there's just 0 and 1, which is 1.

    Okay, so I have these parts: 900, 80, and ____, so that makes _______________.

6. Solve the word problems. 

a. From Flowertown to Princetown is 148 miles.      You travel from Flowertown to Princetown     and back to Flowertown. How many miles is that?

b. The school bought pencils for $128,      pens for $219, and notebooks for $549.       Find the total cost of the items.

c. Find how many feet it is if you walk all of the way     around this triangle.

What numbers are missing from the addition problems?    3    + 1    9 3 9 1 2      +    3  6 5 1 7 1 6 9 +   5   7   4    8 8 + 7       9 0 0

This lesson is taken from Maria Miller's book Math Mammoth Add & Subtract 3, and posted at www.HomeschoolMath.net with permission from the author. Copyright © Maria Miller.

Math Mammoth Add & Subtract 3

A self-teaching worktext for 2nd-3rd grade that covers mental addition & subtraction with three-digit numbers, regrouping with three-digit numbers (carrying and borrowing), rounding, estimating, and word problems.

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