Estimation of whole number addition and subtraction.

Estimation of Whole Number Addition and Subtraction

To estimate means to find an answer that is close to the exact answer. The key with estimation is to only use it in instances that don’t require an exact answer. 

Estimation means to find an answer that makes sense and works with the problem, but is not necessarily exact.

You can estimate sums (the answers to addition problems), and differences (the answers to subtraction problems). The first step in estimating a sum or a difference is to round the numbers, by changing them to the nearest power of ten, hundred, thousand, etc. Round the numbers first, then use mental math to estimate an answer.
When rounding, follow these rounding rules:When rounding, follow these rounding rules:When rounding, follow these rounding rules:
  1. If the number being rounded is less than 5, round down.
  1. If the number being rounded is 5 or greater, round up.

Some key things to think about when estimating:

  1. The estimate must make sense for the problem.
  2. The estimate must be reasonable.
  3. The estimate must be close to the exact answer.
  4. If none of the above fit the estimate,  use exact math for the problem.

Watch the video to know more about rounding numbers.



Solve: Post your answers in the comment box


Comments

  1. Divyanshi 3DOctober 3, 2019 at 5:43 AM

    Estimate the sum by rounding each addend to the nearest ten⤵

    1-20+70=90
    2-780+350=1130
    3-220+80=300
    4-90+40=130
    5-10+710=720
    6-690+150=840

    ReplyDelete
  2. Prithwin, 3COctober 3, 2019 at 11:22 AM

    This comment has been removed by the author.

    ReplyDelete
  3. YuvasriOctober 3, 2019 at 12:02 PM

    This comment has been removed by the author.

    ReplyDelete
  4. YuvasriOctober 3, 2019 at 12:04 PM

    This comment has been removed by the author.

    ReplyDelete
  5. Prithwin, 3COctober 3, 2019 at 12:06 PM

    1) 90
    2) 1130
    3) 300
    4) 130
    5) 720
    6) 840

    ReplyDelete
  6. Nithya 3 AOctober 4, 2019 at 9:09 AM

    1.90
    2.1124
    3.300
    4.130
    5.720
    6.840

    ReplyDelete
  7. UnknownOctober 4, 2019 at 12:06 PM

    Aarush 3A

    90
    1130
    300
    130
    720
    840

    ReplyDelete
  8. YuvasriOctober 4, 2019 at 2:33 PM

    1. 90
    2. 1130
    3. 300
    4. 130
    5. 720
    6. 840

    Yuvasri-3D

    ReplyDelete
  9. Kundan Isha GokulOctober 5, 2019 at 2:01 AM

    1) 20+70=90
    2) 780+350=1130
    3) 220+80=300
    4) 90+40=130
    5) 10+710=720
    6) 690+150=840

    ReplyDelete
  10. UnknownOctober 5, 2019 at 5:58 AM

    Joshua 3A
    90
    1124

    ReplyDelete
  11. UnknownOctober 5, 2019 at 6:27 AM

    Sreelakshmi 3E
    1)90
    2)1130
    3)300
    4)130
    5)750
    6)840

    ReplyDelete
  12. UnknownOctober 5, 2019 at 8:07 AM

    Rohan Suvarna 3A

    1) 20 + 70 = 90
    2) 780 + 350 = 1130
    3) 220 + 80 = 300
    4) 90 + 40 = 130
    5) 10 + 710 = 720
    6) 690 + 150 = 840

    ReplyDelete
  13. Aditi KokareOctober 5, 2019 at 10:08 AM

    Aditi M. Kokare. 3/A

    1) 20+70=90
    2) 780+350=1130
    3) 220+80=300
    4) 90+40=130
    5) 10+710=720
    6) 690+150=840

    ReplyDelete
  14. ABHILASHA MISHRA GR - 3EOctober 5, 2019 at 11:07 AM

    1) 20+70=90
    2) 780+350=1130
    3) 220+80=300
    4) 90+40=130
    5) 10+710=720
    6) 690+150=840

    ReplyDelete
  15. UnknownOctober 5, 2019 at 11:11 AM

    Thanmaya. 3A

    1.90
    2.1130
    3.300
    4.130
    5.720
    6.840

    ReplyDelete
  16. TejuswiniOctober 6, 2019 at 10:05 AM

    1. 80
    2. 1130
    3. 300
    4. 190
    5.720
    6. 840
    Shraddha 3A

    ReplyDelete
  17. Atharva 3AOctober 10, 2019 at 7:45 AM

    [6:01 PM, 10/8/2019] Nandini: 1) 20 + 70 = 90
    2) 780 + 350 = 1130
    3) 220 + 80 = 300
    4) 90 + 40 = 130
    [6:02 PM, 10/8/2019] Nandini: 5) 10 + 710 = 720
    6) 690 + 150 = 840

    ReplyDelete
  18. Aishwarya 3DOctober 11, 2019 at 1:39 AM

    Estimate the sum by rounding

    1) 20+70=90

    2)780+350=1,130

    3)220+80=300

    4)90+40=130

    5)10+710=720

    6)690+150=840

    ReplyDelete
  19. Aarav JoshiOctober 11, 2019 at 3:48 AM

    G-3 W
    a) 20+70=90
    b)780+350=1,130
    c)220+80=300
    d)90+40=130
    e)10+710=720
    f)690+150=840



    ReplyDelete
  20. Amit Anil George, 3HOctober 11, 2019 at 4:05 AM

    1) 20+70=90

    2) 780+350=1130

    3) 220+80=300

    4) 90+40=130

    5) 10+710=720

    6) 690+150=840


    ReplyDelete
  21. Navya 3BOctober 11, 2019 at 10:37 PM

    Navya Grade 3B

    1-20+70=90
    2-780+350=1130
    3-220+80=300
    4-90+40=130
    5-10+710=720
    6-690+150=840

    ReplyDelete
  22. SHREENITHI PRAGATHIOctober 11, 2019 at 11:24 PM

    Shreenithi 3C

    1. 90
    2. 1130
    3. 300
    4. 130
    5. 720
    6. 840

    ReplyDelete
  23. UnknownOctober 11, 2019 at 11:47 PM

    Tarun. M 3R
    1) 90
    2) 1130
    3) 300
    4) 130
    5) 720
    6) 840

    ReplyDelete
  24. UnknownOctober 12, 2019 at 12:22 AM

    Jhanvi Jinlag 3U
    1.90
    2.1130
    3.300
    4.130
    5.720
    6.840

    ReplyDelete
  25. UnknownOctober 12, 2019 at 12:52 AM

    RISHABH-3Q
    1 .80
    2.1130
    3.300
    4.130
    5.720
    6.840

    ReplyDelete
  26. UnknownOctober 12, 2019 at 1:46 AM

    Bhanvi 3A

    1) 20 + 70 = 90
    2) 780 + 350 = 1130
    3) 220 + 80 = 300
    4) 90 + 40 = 130
    5) 10 + 710 = 720
    6) 690 +150 = 840

    ReplyDelete
  27. Izaan 3jOctober 12, 2019 at 2:18 AM

    1. 90
    2. 1130
    3. 300
    4. 130
    5. 720
    6. 840

    ReplyDelete
  28. YASHVARDHAN YADAV 3(A)October 12, 2019 at 2:30 AM

    1. 20+70=90
    2. 780+350=1130
    3. 220+80=300
    4. 90+40=130
    5. 10+710=720
    6. 690+150=840

    ReplyDelete
  29. Karthik AlleOctober 12, 2019 at 3:31 AM

    Karthik (3B)
    1.80
    2.1130
    3.300
    4.130
    5.720
    6.840

    ReplyDelete
  30. Abeer FatmaOctober 12, 2019 at 3:50 AM

    Abeer Fatma 3-Q

    1) 20 + 70 = 90
    2) 780 + 350 = 1130
    3) 220 + 80 = 300
    4) 90 + 40 = 130
    5) 10 + 710 = 720
    6) 690 +150 = 840

    ReplyDelete
  31. UnknownOctober 12, 2019 at 5:53 AM

    yalini 3-w
    1)20+70=90
    2)780+350=1130
    3) 220 + 80 = 300
    4) 90 + 40 = 130
    5) 10 + 710 = 720
    6) 690 +150 = 840

    ReplyDelete
  32. Batul, 3-UOctober 12, 2019 at 7:53 AM

    1. 90
    2. 1130
    3. 300
    4. 130
    5. 780
    6. 800


    ReplyDelete
  33. UnknownOctober 12, 2019 at 8:03 AM

    Arpan Dutta GRADE 3 P
    1.20+70= 90
    2.780+350 = 1130
    3.220+80 =300
    4. 90+ 40= 130
    5 10+710= 720
    6. 690+150 =840

    ReplyDelete
  34. Juwairiyah IfthiquarOctober 12, 2019 at 8:14 AM

    Juwairiyah Ifthiquar 3_R

    1.90
    2.1120
    3.300
    4.130
    5.720
    6.840

    ReplyDelete
  35. SAHANA - 3TOctober 12, 2019 at 8:42 AM

    Q1 .90
    Q2. 1120
    Q3. 300
    Q4. 130
    Q5. 720
    Q6. 840

    ReplyDelete
  36. DenisseOctober 12, 2019 at 9:27 AM

    Denisse 3U

    1) 20+70=90
    2) 780+350=1130
    3) 220+80=300
    4) 90+40=130
    5) 10+710=720
    6) 690+150=840

    ReplyDelete
  37. UnknownOctober 12, 2019 at 9:51 AM

    shrivyshnavi 3R
    1.23+65=88 nearest ten 20+70=90
    2.776+348=1124 nearest ten 780+350=1130
    3.217+82=299 nearest ten 220+80=300
    4.93+36=129 nearest ten 90+40=130
    5.12+708=720 nearest ten 10+710=720
    6.689+153=842 nearest ten 690+150=840

    ReplyDelete
  38. Adithi R Menon, Gr 3ROctober 12, 2019 at 10:23 AM

    1) 20+70=90
    2) 780+350=1130
    3)220+80=300
    4) 90+40=130
    5) 10+710=720
    6) 690+150=840

















    ReplyDelete
  39. Rudra mehtaOctober 12, 2019 at 10:55 AM

    RUDRA 3N
    1) 20+70=90
    2) 780+350=1130
    3) 220+80=300
    4) 90+40=130
    5) 10+710=720
    6) 690+150=840

    ReplyDelete
  40. UnknownOctober 19, 2019 at 2:20 AM

    Anirban 3-B

    1) 20+70=90
    2) 780+350=1130
    3) 220+80=300
    4) 90+40=130
    5) 10+710=720
    6) 690+150=840

    ReplyDelete
  41. UnknownOctober 19, 2019 at 5:01 AM

    1) 20+70=90
    2) 780+350=1130
    3) 220+80=300
    4) 90+40=130
    5) 10+710=720
    6) 690+150=840

    UMER 3U

    ReplyDelete
  42. UnknownOctober 19, 2019 at 12:18 PM

    Juwan bibin 3B

    1) 90
    2)1130
    3) 300
    4)130
    5)720
    6)840

    ReplyDelete
  43. NeethaOctober 27, 2019 at 7:46 AM

    Shravan Kaushik 3J

    1] 90
    2]1130
    3] 300
    4]130
    5]720
    6]840

    ReplyDelete
  44. UnknownOctober 28, 2019 at 1:22 AM

    Basil Varghese Ninan

    20+70=90
    780+350=1130
    220+80=300
    90+40=130
    10+710=720
    690+150=840

    ReplyDelete

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