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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 77 · 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 273 + 761? (a) 900 (b) 1300 (c) 1100
  2. 2.Best estimate of 32 × 97? (a) 3000 (b) 300 (c) 30000
  3. 3.Best estimate of 89 × 66? (a) 6300 (b) 63000 (c) 630
  4. 4.Best estimate of 604 + 658? (a) 1500 (b) 1300 (c) 1100
  5. 5.Best estimate of 52 × 48? (a) 2500 (b) 250 (c) 25000
  6. 6.Best estimate of 837 + 122? (a) 700 (b) 1100 (c) 900
  7. 7.Best estimate of 12 × 66? (a) 70 (b) 700 (c) 7000
  8. 8.Best estimate of 266 + 200? (a) 700 (b) 300 (c) 500
  9. 9.Best estimate of 48 × 31? (a) 15000 (b) 1500 (c) 150
  10. 10.Best estimate of 73 × 73? (a) 490 (b) 49000 (c) 4900
  11. 11.Best estimate of 77 × 46? (a) 4000 (b) 400 (c) 40000
  12. 12.Best estimate of 47 × 26? (a) 15000 (b) 1500 (c) 150
  13. 13.Best estimate of 565 + 602? (a) 1200 (b) 1400 (c) 1000
  14. 14.Best estimate of 183 + 810? (a) 800 (b) 1200 (c) 1000
  15. 15.Best estimate of 437 + 151? (a) 800 (b) 400 (c) 600
  16. 16.Best estimate of 66 × 66? (a) 4900 (b) 49000 (c) 490
  17. 17.Best estimate of 17 × 13? (a) 2000 (b) 20 (c) 200
  18. 18.Best estimate of 92 × 96? (a) 9000 (b) 90000 (c) 900
  19. 19.Best estimate of 72 × 44? (a) 28000 (b) 280 (c) 2800
  20. 20.Best estimate of 39 × 78? (a) 3200 (b) 32000 (c) 320
  21. 21.Best estimate of 50 × 33? (a) 1500 (b) 15000 (c) 150
  22. 22.Best estimate of 158 + 220? (a) 200 (b) 600 (c) 400
  23. 23.Best estimate of 88 × 40? (a) 3600 (b) 36000 (c) 360
  24. 24.Best estimate of 16 × 51? (a) 1000 (b) 100 (c) 10000
  25. 25.Best estimate of 68 × 19? (a) 1400 (b) 140 (c) 14000
  26. 26.Best estimate of 40 × 49? (a) 200 (b) 20000 (c) 2000
  27. 27.Best estimate of 71 × 13? (a) 7000 (b) 700 (c) 70
  28. 28.Best estimate of 471 + 689? (a) 1200 (b) 1000 (c) 1400
  29. 29.Best estimate of 80 × 59? (a) 480 (b) 4800 (c) 48000
  30. 30.Best estimate of 604 + 515? (a) 1300 (b) 900 (c) 1100
  31. 31.Best estimate of 18 × 80? (a) 160 (b) 1600 (c) 16000
  32. 32.Best estimate of 239 + 184? (a) 600 (b) 200 (c) 400
  33. 33.Best estimate of 19 × 61? (a) 1200 (b) 120 (c) 12000
  34. 34.Best estimate of 19 × 62? (a) 1200 (b) 120 (c) 12000
  35. 35.Best estimate of 308 + 155? (a) 500 (b) 300 (c) 700
  36. 36.Best estimate of 639 + 257? (a) 900 (b) 700 (c) 1100
  37. 37.Best estimate of 44 × 56? (a) 240 (b) 2400 (c) 24000
  38. 38.Best estimate of 96 × 14? (a) 1000 (b) 100 (c) 10000
  39. 39.Best estimate of 690 + 771? (a) 1300 (b) 1700 (c) 1500
  40. 40.Best estimate of 464 + 834? (a) 1500 (b) 1100 (c) 1300

Answer key

  1. 1100
  2. 3000
  3. 6300
  4. 1300
  5. 2500
  6. 900
  7. 700
  8. 500
  9. 1500
  10. 4900
  11. 4000
  12. 1500
  13. 1200
  14. 1000
  15. 600
  16. 4900
  17. 200
  18. 9000
  19. 2800
  20. 3200
  21. 1500
  22. 400
  23. 3600
  24. 1000
  25. 1400
  26. 2000
  27. 700
  28. 1200
  29. 4800
  30. 1100
  31. 1600
  32. 400
  33. 1200
  34. 1200
  35. 500
  36. 900
  37. 2400
  38. 1000
  39. 1500
  40. 1300

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