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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 143 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 87 × 98? (a) 90000 (b) 900 (c) 9000
  2. 2.Best estimate of 216 + 308? (a) 700 (b) 300 (c) 500
  3. 3.Best estimate of 263 + 825? (a) 1300 (b) 900 (c) 1100
  4. 4.Best estimate of 12 × 23? (a) 200 (b) 20 (c) 2000
  5. 5.Best estimate of 625 + 209? (a) 800 (b) 600 (c) 1000
  6. 6.Best estimate of 330 + 371? (a) 900 (b) 700 (c) 500
  7. 7.Best estimate of 47 × 18? (a) 10000 (b) 1000 (c) 100
  8. 8.Best estimate of 454 + 804? (a) 1500 (b) 1300 (c) 1100
  9. 9.Best estimate of 77 × 74? (a) 5600 (b) 56000 (c) 560
  10. 10.Best estimate of 98 × 49? (a) 500 (b) 5000 (c) 50000
  11. 11.Best estimate of 56 × 31? (a) 18000 (b) 1800 (c) 180
  12. 12.Best estimate of 57 × 89? (a) 540 (b) 5400 (c) 54000
  13. 13.Best estimate of 843 + 192? (a) 1000 (b) 1200 (c) 800
  14. 14.Best estimate of 94 × 60? (a) 5400 (b) 540 (c) 54000
  15. 15.Best estimate of 383 + 518? (a) 1100 (b) 700 (c) 900
  16. 16.Best estimate of 392 + 834? (a) 1200 (b) 1400 (c) 1000
  17. 17.Best estimate of 16 × 58? (a) 1200 (b) 120 (c) 12000
  18. 18.Best estimate of 149 + 446? (a) 500 (b) 300 (c) 700
  19. 19.Best estimate of 76 × 31? (a) 240 (b) 24000 (c) 2400
  20. 20.Best estimate of 452 + 222? (a) 700 (b) 900 (c) 500
  21. 21.Best estimate of 253 + 228? (a) 700 (b) 300 (c) 500
  22. 22.Best estimate of 627 + 186? (a) 600 (b) 1000 (c) 800
  23. 23.Best estimate of 720 + 554? (a) 1500 (b) 1100 (c) 1300
  24. 24.Best estimate of 700 + 835? (a) 1300 (b) 1500 (c) 1700
  25. 25.Best estimate of 39 × 71? (a) 28000 (b) 280 (c) 2800
  26. 26.Best estimate of 68 × 71? (a) 49000 (b) 490 (c) 4900
  27. 27.Best estimate of 86 × 88? (a) 81000 (b) 8100 (c) 810
  28. 28.Best estimate of 129 + 264? (a) 400 (b) 600 (c) 200
  29. 29.Best estimate of 243 + 830? (a) 800 (b) 1200 (c) 1000
  30. 30.Best estimate of 357 + 514? (a) 1100 (b) 900 (c) 700
  31. 31.Best estimate of 23 × 36? (a) 800 (b) 80 (c) 8000
  32. 32.Best estimate of 76 × 61? (a) 48000 (b) 4800 (c) 480
  33. 33.Best estimate of 840 + 678? (a) 1500 (b) 1700 (c) 1300
  34. 34.Best estimate of 817 + 602? (a) 1200 (b) 1600 (c) 1400
  35. 35.Best estimate of 355 + 301? (a) 900 (b) 700 (c) 500
  36. 36.Best estimate of 82 × 98? (a) 800 (b) 80000 (c) 8000
  37. 37.Best estimate of 612 + 258? (a) 900 (b) 1100 (c) 700
  38. 38.Best estimate of 29 × 52? (a) 1500 (b) 15000 (c) 150
  39. 39.Best estimate of 711 + 198? (a) 1100 (b) 900 (c) 700
  40. 40.Best estimate of 73 × 21? (a) 1400 (b) 140 (c) 14000

Answer key

  1. 9000
  2. 500
  3. 1100
  4. 200
  5. 800
  6. 700
  7. 1000
  8. 1300
  9. 5600
  10. 5000
  11. 1800
  12. 5400
  13. 1000
  14. 5400
  15. 900
  16. 1200
  17. 1200
  18. 500
  19. 2400
  20. 700
  21. 500
  22. 800
  23. 1300
  24. 1500
  25. 2800
  26. 4900
  27. 8100
  28. 400
  29. 1000
  30. 900
  31. 800
  32. 4800
  33. 1500
  34. 1400
  35. 700
  36. 8000
  37. 900
  38. 1500
  39. 900
  40. 1400

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