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Learn what to do when you have more than 10 ones and need to move them to the tens place.
Imagine you are collecting shiny gold coins. Your pocket can only hold 9 coins before it gets too heavy. What happens when you find your 10th coin? You get to trade them for a magic gold bar!
In math, every number has a 'house' or a place value. The ones place is like a small room that can only hold up to 9 items. As soon as you get 10 items, they must be bundled together to form a single ten. This is called regrouping. Think of it like trading 10 pennies for 1 dime. You have the same amount of money, but it's easier to carry! When we add numbers like , we get . Since is more than , we take of those ones and move them to the tens place.
Quick Check
If you have 14 ones, how many 'tens' can you make, and how many 'ones' are left over?
Answer
You can make 1 ten, with 4 ones left over.
When we write addition problems vertically, we line up the ones and the tens in columns. We always start adding from the right side (the ones column). If the total in the ones column is or more, we write the extra ones at the bottom and 'carry' the new ten to the top of the tens column. This ensures we don't forget to count that new ten we just created!
Let's solve : 1. Add the ones: . 2. Since is more than , we regroup. is ten and ones. 3. Write the in the ones place. 4. Carry the ten to the top of the tens column. 5. Add the tens: (carried) . 6. The final answer is .
Quick Check
When adding , what is the first step?
Answer
Add the ones column ().
Now that you know the secret of the 'carry,' you can add any two-digit numbers! Just remember the golden rule: Add ones first, then add tens. If your ones add up to something like , the stays in the ones place and the (representing the ten) jumps over to join its friends in the tens column.
Solve : 1. Add the ones: . 2. Write in the ones place and carry the to the tens column. 3. Add all the tens together: (carried) . 4. The total is .
Even when we work with three-digit numbers (hundreds), the regrouping rule stays the same. If the ones column gets too full, we move a ten to the tens column. For now, we will focus on problems where we only need to regroup once. It's like building a tower—you just keep stacking the blocks in the right spots!
Solve : 1. Add the ones: . 2. Write in the ones place, carry the to the tens place. 3. Add the tens: (carried) . 4. Look at the hundreds place: there is only a . 5. Bring the down to the hundreds place. 6. The final answer is .
What is ?
If you add , what digit will be in the ones place of your answer?
True or False: You should always add the tens column before the ones column.
Review Tomorrow
Tomorrow, try to explain to a friend or a stuffed animal why we 'carry the one' when adding .
Practice Activity
Find a handful of small items (like beans or LEGOs). Group them into piles of 10 and see how many 'tens' and 'ones' you have!