Add It Up
Find the sum: 24,386 + 13,427
“What is 37,813?”
Find the difference: 48,732 - 16,421
What is 32,311
A library has 1,245 books and receives 328 more. How many books does it have now?
"What is 1,573 books?"
A student says 23,458 + 12,341 = 35,799. Is the answer correct? If not, give the correct sum.
"What is 35,799?"
23,458+12,341= 37,799?
Estimate 39,412 + 21,285 by rounding each number to the nearest ten thousand. What is a reasonable estimate?
"What is about 60,000?"
Find the sum: 46,758 + 28,369
“What is 75,127?”
Find the difference: 72,305 - 28,647
"What is 43,658"
A school collected 1,640 cans on Monday. On Tuesday, it collected 275 fewer cans. How many cans did it collect altogether? Write an equation using c for the total.
"What is 3,005 cans?"
1,640+(1,640-275)= c
A student says 46,275 + 28,649 = 74,814. Which error best explains the mistake?
A. The student added instead of subtracting.
B. The student forgot to add a regrouped 1 in the hundreds place.
C. The student started in the wrong place.
D. The student regrouped 10 ones as 1 hundred.
"What is B?"
Correct sum : 46,275+28,649=74,924
The student's answer is short by 110 consistent with forgetting a regrouped 1 in the hundreds place.
A student estimates 68,432 - 29,718 as about 40,000. Is that reasonable? Use rounding to explain.
"What is yes; about 40,000?'"
68,000~70,000 and 29,718~30,000
Estimated difference 70,000-30,000= 40,000
Find the missing addend: 37,845 + n = 82,106
“What is 44,261?”
Find the difference: 91,004 - 46,758
"What is 44,246?"
Jordan had 562 stickers, gave away 147, and then received 208 more. How many stickers does Jordan have now?
"What is 623 stickers?"
562-147=415, then 415+208= 623
A student says 63,204 - 27,586 = 45,722. Find the correct difference.
"What is 35,618?"
63,204-27,586= 35,618
A store had 5,826 notebooks and sold 2,143. A student says 8,000 notebooks remain. Is the answer reasonable? Explain with an estimate.
"What is no?"
The exact number remaining is 5,826-2,143=3,683.
An estimate is about 6,000-2,000=4,000, not 8,000
Find the sum: 58,697 + 36,845
“What is 95,542?”
80,013 - 37,586
"What is 42,427?"
A school has 2,760 markers. It uses 960, then shares the rest equally among 12 classrooms. How many markers does each classroom receive?
"What is 150 markers per classroom?"
2760-960=1,800. Then divide equally 1,800/12=150
A student adds 38,756 + 24,687 and writes 52,443. What regrouping mistake may have caused the error?
"What is forgetting to add a regrouped 1
Correct sum: 38,756 + 24,687= 63,443
Student's answer, 52,443, is 11,000 too small, suggesting regrouped 1 was not included when adding the thousands.
A town collected 1,684 cans in week one and 297 fewer cans in week two. A student says the total was 3,371 cans. Is the answer reasonable? Give an estimate.
"What is no; the total is about 3,100 cans?"
Week 2 is about 1,700-300=1,400.
The total is about 1,700+1,400= 3,100, not 3,371. The exact total is 1,684+(1,684-297)=3,071
Find the missing addend: n + 47,586 = 103,204
“What is 55,618?”
Find the difference: 100,000 - 58,739
"What is 41, 261?"
A supply room has 1,386 notebooks. It receives 9 boxes with 24 notebooks in each box. How many notebooks are there now?
"What is 1,602 notebooks.
9x24= 216 notebooks. Then 1,386+216=1,602
A student says 74,628 + 18,795 = 83,313. Find the correct sum and identify the likely regrouping error.
"What is 93,423
74,628+18,795=93,423
The stated answer is 10,110 too small; students should check where regrouped values were added across place values.
A school collected 1,736 books from fourth grade. Fifth grade collected 284 fewer books. A student says the grades collected 3,188 books altogether. Choose TWO statements that show the answer is not reasonable.
A. Fifth grade collected about 1,500 books, so the total should be about 3,200 books.
B. Fifth grade collected about 1,500 books, so the total should be about 3,000 books.
C. Since 284 is less than 1,736, the total must be less than 1,736 books.
D. Fourth grade collected about 1,700 books and fifth grade about 1,400 books, so the total should be about 3,100 books.
E. The total should be about 2,000 books because 1,700 - 300 = 1,400.
"What are A and B?"
Fifth grade collected 1,736-284=1,452 books. The exact to; total is 1,736+1,452=3,188. Option B estimates the total at about 3,000, and option D estimates it at 3,100. Option A incorrectly estimates fifth grade at about 1,500 and total at about 3,200; C makes an unsupported claim.