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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 459 · 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 22 × 24? (a) 400 (b) 40 (c) 4000
  2. 2.Best estimate of 386 + 536? (a) 900 (b) 1100 (c) 700
  3. 3.Best estimate of 642 + 632? (a) 1000 (b) 1200 (c) 1400
  4. 4.Best estimate of 77 × 62? (a) 480 (b) 48000 (c) 4800
  5. 5.Best estimate of 92 × 26? (a) 27000 (b) 2700 (c) 270
  6. 6.Best estimate of 94 × 53? (a) 4500 (b) 45000 (c) 450
  7. 7.Best estimate of 542 + 582? (a) 1100 (b) 1300 (c) 900
  8. 8.Best estimate of 70 × 92? (a) 6300 (b) 630 (c) 63000
  9. 9.Best estimate of 172 + 632? (a) 600 (b) 1000 (c) 800
  10. 10.Best estimate of 37 × 26? (a) 120 (b) 1200 (c) 12000
  11. 11.Best estimate of 49 × 28? (a) 150 (b) 1500 (c) 15000
  12. 12.Best estimate of 407 + 572? (a) 1200 (b) 1000 (c) 800
  13. 13.Best estimate of 247 + 765? (a) 1200 (b) 1000 (c) 800
  14. 14.Best estimate of 14 × 73? (a) 700 (b) 7000 (c) 70
  15. 15.Best estimate of 168 + 314? (a) 500 (b) 700 (c) 300
  16. 16.Best estimate of 186 + 707? (a) 1100 (b) 700 (c) 900
  17. 17.Best estimate of 71 × 36? (a) 28000 (b) 2800 (c) 280
  18. 18.Best estimate of 29 × 51? (a) 150 (b) 1500 (c) 15000
  19. 19.Best estimate of 339 + 407? (a) 700 (b) 500 (c) 900
  20. 20.Best estimate of 26 × 23? (a) 6000 (b) 600 (c) 60
  21. 21.Best estimate of 96 × 13? (a) 100 (b) 1000 (c) 10000
  22. 22.Best estimate of 81 × 22? (a) 16000 (b) 1600 (c) 160
  23. 23.Best estimate of 21 × 89? (a) 1800 (b) 180 (c) 18000
  24. 24.Best estimate of 386 + 274? (a) 500 (b) 700 (c) 900
  25. 25.Best estimate of 467 + 681? (a) 1200 (b) 1000 (c) 1400
  26. 26.Best estimate of 151 + 483? (a) 500 (b) 900 (c) 700
  27. 27.Best estimate of 842 + 386? (a) 1400 (b) 1200 (c) 1000
  28. 28.Best estimate of 50 × 90? (a) 450 (b) 45000 (c) 4500
  29. 29.Best estimate of 874 + 477? (a) 1400 (b) 1200 (c) 1600
  30. 30.Best estimate of 89 × 79? (a) 7200 (b) 72000 (c) 720
  31. 31.Best estimate of 323 + 302? (a) 800 (b) 600 (c) 400
  32. 32.Best estimate of 451 + 716? (a) 1200 (b) 1000 (c) 1400
  33. 33.Best estimate of 257 + 597? (a) 1100 (b) 900 (c) 700
  34. 34.Best estimate of 22 × 58? (a) 1200 (b) 12000 (c) 120
  35. 35.Best estimate of 63 × 71? (a) 42000 (b) 420 (c) 4200
  36. 36.Best estimate of 44 × 70? (a) 280 (b) 2800 (c) 28000
  37. 37.Best estimate of 82 × 98? (a) 800 (b) 8000 (c) 80000
  38. 38.Best estimate of 516 + 513? (a) 1200 (b) 800 (c) 1000
  39. 39.Best estimate of 46 × 67? (a) 350 (b) 3500 (c) 35000
  40. 40.Best estimate of 39 × 48? (a) 20000 (b) 2000 (c) 200

Answer key

  1. 400
  2. 900
  3. 1200
  4. 4800
  5. 2700
  6. 4500
  7. 1100
  8. 6300
  9. 800
  10. 1200
  11. 1500
  12. 1000
  13. 1000
  14. 700
  15. 500
  16. 900
  17. 2800
  18. 1500
  19. 700
  20. 600
  21. 1000
  22. 1600
  23. 1800
  24. 700
  25. 1200
  26. 700
  27. 1200
  28. 4500
  29. 1400
  30. 7200
  31. 600
  32. 1200
  33. 900
  34. 1200
  35. 4200
  36. 2800
  37. 8000
  38. 1000
  39. 3500
  40. 2000

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