The big ideaOnes with ones, tens with tens. Ten ones make one ten.
How it works
Add the ones first. Then add the tens.
Sometimes the ones make 10 or more. Ten ones are the same as one ten, so bundle them: keep the ones that are left, and move the new ten over to the tens.
Then add the tens, and count the ten you moved. Writing it down in a column keeps every digit in its own place.
Another way to see it: hop to the next ten, then hop the rest.
Example 1: Add 26 and 7
26 + 7 = ?
Ones first: 6 + 7 = 13.
13 is one ten and 3 ones. Write 3 under the ones, and move the ten over to the tens.
Now the tens: the 1 you moved and the 2 that were there make 3 tens.
3 tens and 3 ones: 33.
6 ones and 7 ones make 13. Ten of them bundle into one new ten (in gold).
Example 2: Add 38 and 45: tens on both sides
38 + 45 = ?
Ones first: 8 + 5 = 13. Write 3 and move a ten over.
Tens: the 1 you moved, 3 and 4 make 8 tens.
8 tens and 3 ones: 83.
8 ones and 5 ones make 13, so a new ten is made (gold).
Example 3: Add 34 and 25: when nothing needs to move
34 + 25 = ?
Ones first: 4 + 5 = 9. That is less than ten, so there is no ten to move.
Tens: 3 and 2 make 5 tens.
5 tens and 9 ones: 59.
4 ones and 5 ones make 9. No new ten, so nothing turns gold.
Words to know
regroup
Swap ten ones for one ten (or one ten for ten ones).
column
Numbers lined up one above the other: ones under ones, tens under tens.
carry
The new ten you move over to the tens place.
Watch out
Write only the 3 under the ones. If you write the whole 13 there, the ten has nowhere to go.
Don't forget the ten you moved. It still counts when you add the tens.
Line the numbers up on the right, so ones sit under ones and tens sit under tens.
Try it
38 + 45 = ?
59 + 26 = ?
27 + 8 = ?
Answers: 1. 83 · 2. 85 · 3. 35
For grown-upsBuild it before you write it. Use ten sticks bundled with elastic bands and some loose ones: add 26 and 7, then bundle ten loose ones into a new ten. Once your child has seen ten ones become one ten, the column is just a way of writing down what they already did.
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