Subtracting Two-Digit Numbers Using Base Ten Blocks with Regrouping

Mr. Squeaks is helping with the annual Rubber Duck Race... but things have gotten out of hand. "Malfunction, malfunction!" Good thing Mr. Squeaks has this net so he can take out all the extra ducks! But how many ducks are left? In order to see how many ducks we have for the race, Mr. Squeaks needs our help with... "Subtracting Two-Digit Numbers using Base Ten Blocks with Regrouping". Mr. Squeaks placed seventy-five rubber ducks in the water, and took eighteen out. Let's subtract eighteen from seventy-five using base ten blocks on a place value chart to see how many are left. We can use a place value chart and base ten blocks to model subtraction. These tools help us see what's happening when we regroup, or borrow. The first step is to represent how many ducks they started with. There were seventy-five in the water, so we'll use base ten blocks to represent seventy-five. Since there is a seven in the tens place, (...) we put seven TENS in the TENS column. (...) There is a five in the ones place, (...) so we put five ONES in the ONES column. (...) The second step is to subtract eighteen starting with the ones place (...) so subtract eight from five. WAIT, we can't take away eight blocks because there are only five! Since there is not enough blocks to take away, (...) we regroup, or borrow, a ten from the tens place (...) and break it into ten ones. Now there are fifteen blocks in the ones place that we can subtract eight from. If we take eight ONES from the ones place, (...) we have seven left. Write seven in the ones place HERE. The third step is to subtract the tens place, so subtract one TEN (...) from six TENS. If we take one TEN from the tens place, we have five left. Write five in the tens place HERE. Seventy-five minus eighteen is fifty-seven... but fifty-seven rubber ducks is still too many! Mr. Squeaks takes out thirty-nine more. Let's subtract thirty-nine from fifty-seven to see how many ducks are left. First, represent fifty-seven using base ten blocks. What number is in the tens place? (...) There is a five in the tens place, (...) so we put five TENS in the TENS place. (...) What number is in the ones place? (...) There is a seven in the ones place, (...) so we put seven ONES in the ONES place. (...) The second step is to subtract thirty-nine starting with the ones place (...) so subtract nine from seven. Can we subtract nine blocks from seven blocks? (...) No, we can't take away nine blocks because there are only seven. What can we do? (...) We can REGROUP a ten from the tens place (...) and break it into ten ones. Now, there are seventeen blocks in the ones place we can take away nine from. If we take nine ONES from the ones place, (...) we have eight left. Write eight in the ones place HERE. The third step is to subtract the tens place, so subtract three TENS from four TENS. If we take three TENS from the tens place, we have one left. Write one in the tens place HERE. Fifty-seven minus thirty-nine is eighteen... so there are eighteen rubber ducks left. Before we see if that's the right amount for the race, let's summarize. Remember (...) when subtracting two-digit numbers using base ten blocks with regrouping... the first step is to represent the number we started with on the place value chart (...) using base ten blocks. Next, regroup from the tens place if you need to, (...) and then subtract the ones place. Write the difference in the ones place HERE. Third, subtract the tens place and write the difference below. The number remaining is the answer. It looks like Mr. Squeaks wants to add one last rubber duck! "Oops!"