Assessing the Reasonableness of Sums with Rounding

The video tutorial explains how to assess the reasonableness of sums by using rounding. It introduces the concept of rounding to the leftmost place of the smallest number to ensure consistency. Two examples are provided: Lucinda's problem, where rounding to the nearest ten confirms her sum is reasonable, and Tasha's problem, where rounding to the hundreds place reveals a significant error. The lesson concludes by reinforcing the importance of checking the reasonableness of sums using rounding.

What is one method to verify if an answer to an addition problem is reasonable?

• Round the numbers to the nearest hundred.

• Subtract the numbers and check the difference.

• Recalculate the sum using a calculator.

• Round the numbers to the leftmost place of the smallest number.

In Lucinda's problem, what is the rounded sum of 378 and 41?

• 440

• 410

• 420

• 430

Why was Lucinda's answer considered reasonable?

• Her answer was very close to the estimated sum.

• Her answer was less than the estimated sum.

• Her answer was exactly the same as the estimated sum.

• Her answer was more than the estimated sum.

In Tasha's problem, to which place should the numbers be rounded?

• Tens place

• Thousands place

• Hundreds place

• Units place

What was the main issue with Tasha's answer?

• She used a calculator incorrectly.

• She added the numbers incorrectly.

• She rounded the numbers to the wrong place.

• Her answer was significantly different from the estimated sum.