Add: 57 + 86

Question

Estimate: 57 + 86
_ + 90 = 150
We can expect the estimate to be _ than the actual sum.
Set the problem up vertically. Line up the numbers by place value: ones over ones and tens over tens.
Add:
7 + 6 = _
10 + 50 + 80 = _
The total in the tool is _.
This is close to our estimate of 150.

Answer 1

Let's break this down step by step:

1. Add:
   \( 57 + 86 \)

   Line up the numbers by place value:

   57
   

   • 86

   ---

   Now, adding the ones column:

   • \( 7 + 6 = 13 \) (write down 3 and carry over 1)

   Add the tens column:

   • \( 5 + 8 + 1 = 14 \)

   So, the total is: \( 143 \)

2. Estimate:
   For estimating \( 57 + 86 \), we can round:

   • \( 57 \) rounds to \( 60 \)
   • \( 86 \) rounds to \( 90 \)

   So, \( 60 + 90 = 150 \).

3. Find the missing number (_):
   To fill in the blank \( _ + 90 = 150 \): \( 150 - 90 = 60 \)
   So, the missing number is \( 60 \).

4. Expectations about the estimate vs. actual sum:
   We can expect the estimate to be greater than the actual sum. (Since \( 150 \) is greater than \( 143 \)).

5. Setting the problem up vertically again for clarity:

   57
   

   • 86

   ---

   • Adding again: \( 7 + 6 = 13 \) (write down 3 and carry over 1) \( 5 + 8 + 1 = 14 \)

   Thus, the total is still \( 143 \).

6. Summarizing:

   • The total in the tool is 143.
   • This is close to our estimate of 150.

Final answers:

• Estimated sum: \( 150 \)
• Actual sum: \( 143 \)
• Difference between estimate and actual: Estimate is greater.