Subtraction within 1,000: Regrouping Tens from Hundreds

Free sample questions, a clear explanation, and 5 practice skills with an AI tutor that guides without giving the answer away.

Unlocking the Hundreds: Your Subtraction Superpower!

Hey Math Explorer! Have you ever tried to pay for a small toy with a big $100 bill? You can't just tear a piece off! You have to trade it for smaller bills, like ten $10 bills. Guess what? Subtracting big numbers works the exact same way! We call this "regrouping," and it's like being a money-trading expert.

Let's Solve a Farm Fresh Problem!

A farmer had 540 apples and sold 170. How many are left? Let's find out!

We set up our problem: 540 - 170. We start with the ones: 0 - 0 is 0. Easy! But wait... look at the tens place. We have 4 tens (40) but we need to take away 7 tens (70). We don't have enough!

Don't worry! We just need to go next door to the hundreds place. Think of it like this: we knock on the door of the 5 hundreds and say, "Excuse me, Mr. Hundred! Can we trade one of your hundred flats for 10 ten rods?"

Of course! The hundreds place shares one of its hundreds. So, the 5 hundreds becomes 4 hundreds. That hundred we "borrowed" magically transforms into 10 new tens! We add these to the 4 tens we already had. Now we have 10 + 4 = 14 tens. Plenty! Now we can easily subtract: 14 tens - 7 tens = 7 tens.

Key Takeaway!

Regrouping is just making a fair trade. When you don't have enough tens, you trade 1 Hundred for 10 Tens.

Your Steps to Success!

Whether you're using base-ten blocks, drawing pictures, or using the standard algorithm, the steps are the same. You can even draw a bar model to see the "whole" (540) and the "part" you're taking away (170).

Step 1: Stack your numbers and start in the ones place.
Step 2: Move to the tens place. If the top number is smaller than the bottom, it's time to regroup!
Step 3: Go to the hundreds place. Cross out the digit, make it one less, and give 10 tens to the tens place.
Step 4: Now subtract the tens, then the hundreds. You did it!

So, our farmer has 540 - 170 = 370 apples left. Awesome job helping out! Keep practicing, and you'll be a regrouping rockstar in no time!

Sample questions

1. You have 3 hundred blocks, 4 ten blocks, and 5 one blocks. You need to take away 1 hundred block, 7 ten blocks, and 2 one blocks. What do you do first to take away the 7 ten blocks?

○ A. Take away 2 one blocks from 5 one blocks.

○ B. Take away 1 hundred block from 3 hundred blocks.

✓ C. Break 1 hundred block into 10 ten blocks.

○ D. Add 10 ten blocks to the 4 ten blocks.

Answer: C. Break 1 hundred block into 10 ten blocks. — Remember, you can't take 7 ten blocks from 4 ten blocks. What do you do with a hundred block to get more tens?

2. Imagine you have 4 hundred blocks, 2 ten blocks, and 8 one blocks. You want to subtract 1 hundred block, 5 ten blocks, and 3 one blocks. After you regroup 1 hundred block into 10 ten blocks, how many ten blocks do you have now?

○ A. 5 ten blocks

○ B. 7 ten blocks

○ C. 10 ten blocks

✓ D. 12 ten blocks

Answer: D. 12 ten blocks — When you break 1 hundred block into 10 ten blocks, don't forget to add them to the ten blocks you already have!

3. You have 5 hundred blocks, 3 ten blocks, and 6 one blocks. You need to subtract 2 hundred blocks, 8 ten blocks, and 1 one block. After regrouping 1 hundred block for 10 ten blocks, what is the new number of hundred blocks you have?

✓ A. 4 hundred blocks

○ B. 5 hundred blocks

○ C. 3 hundred blocks

○ D. 13 hundred blocks

Answer: A. 4 hundred blocks — If you take 1 hundred block to make more tens, how many hundred blocks are left?

Skills in this topic

Subtract numbers involving regrouping tens from hundreds using concrete base-ten blocks.
Represent subtraction with regrouping tens from hundreds using pictorial models.
Subtract two 3-digit numbers with regrouping tens from hundreds using the standard algorithm.
Solve subtraction word problems involving regrouping tens from hundreds using bar models.
A farmer had 540 apples and sold 170. How would you explain the 'borrowing' process for the tens place to someone who is confused?

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