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Estimation in Word Problems

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Estimation in Word Problems
CCSS.MATH.CONTENT.4.NBT.A.3

Basics on the topic Estimation in Word Problems

***Estimation in Word Problems

In word problems, checking our work for reasonableness is a useful skill. We can use estimation strategies such as rounding or compatible numbers with mental computation. First, read and then reread the problem to identify the numbers used for computation. Then, use rounding or compatible numbers. Next, use mental math to find an estimate. Finally, compare the estimation to the original answer to determine reasonableness. If the numbers are close, your math is most likely correct. If the numbers are far apart, your math most likely has a mistake and needs to be corrected.

Transcript Estimation in Word Problems

Welcome to 'Sense or No Sense!' Mr. Squeaks and Imani must determine the reasonableness of answers to word problems! In order to win the prize, they will need to use "Estimation in Word Problems." In word problems, checking our work for reasonableness is a useful skill. We can use estimation strategies such as rounding or compatible numbers and mental computation. First, read and then reread the problem to identify the numbers used for computation. Then, use rounding or compatible numbers. Next, use mental math to find an estimate. Finally, compare the estimation to the original answer to determine reasonableness. If the numbers are close, your math is most likely correct. If the numbers are far apart, your math most likely has a mistake and needs to be corrected. Here's the first question. Axel and Tank plan a family trip to Submersive Studios. Admission is sixty-seven dollars and ninety-nine cents for adults, and forty-two dollars and ninety-nine cents for children. Four adults and two children are going. Axel says it will cost three hundred fifty-seven dollars and ninety-four cents altogether. Does his answer make sense...or no sense? To determine the reasonableness of this answer, they will estimate. Sixty-seven dollars and ninety-nine cents is rounded to seventy dollars. There are four tickets at this price. Seventy times four equals two hundred eighty. Forty-two dollars and ninety-nine cents is COMPATIBLE with forty-five. Forty-five times two is ninety. Two hundred eighty plus ninety equals three hundred seventy dollars. Three hundred seventy dollars is close to three hundred fifty-seven dollars and ninety-four cents, so Axel's answer is reasonable. " SENSE!" The next round is worth DOUBLE and here is the question! Zuri and Freddie collected cans to recycle. Zuri collected six boxes with twenty-four cans in each. Freddie collected four boxes with thirty-seven cans in each. Freddie says he collected two hundred ninety-two MORE cans than Zuri. Does his answer make sense... "SENSE!" Mr. Squeaks answered incorrectly because he rushed and didn't check reasonableness. Here is how estimation would have helped. Zuri had six boxes of twenty-four cans. What number is COMPATIBLE with twenty-four? Twenty-five. What is six times twenty-five? One hundred fifty. Freddie had four boxes of thirty-seven cans. What number do we round thirty-seven to? Forty. What is four times forty? One hundred sixty. The question asks how many MORE, so we subtract. What is one hundred sixty minus one hundred fifty? Ten. Freddie's answer was NOT reasonable because he used addition instead of subtraction. It's the final round they must get this correct or leave empty-handed! Nari and Gus are planning a cookout. They invited twenty-eight guests and want to have enough for two hot dogs each. Hot dogs come in packs of twelve. Nari says they need to buy five packs. Does his answer make sense...or no sense? Pause the video and solve this problem to see what they SHOULD answer and press play when you are ready for the solution! Twenty-eight rounds to thirty. Thirty times two equals sixty. Twelve and five ARE compatible numbers, so multiply them together to get sixty. While they debate their answer, let's review! Remember, In word problems, checking our work for reasonableness is a useful skill. First, read and reread the problem to identify the numbers used for computation. Then round or change the larger numbers to compatible numbers. Next, use mental math to find an estimate. Finally, compare the estimation to the original answer to determine reasonableness. Congratulations Imani and you too, Mr. Squeaks!