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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 235 · 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 88 × 47? (a) 4500 (b) 450 (c) 45000
  2. 2.Best estimate of 191 + 587? (a) 800 (b) 1000 (c) 600
  3. 3.Best estimate of 38 × 21? (a) 80 (b) 800 (c) 8000
  4. 4.Best estimate of 38 × 40? (a) 16000 (b) 1600 (c) 160
  5. 5.Best estimate of 677 + 878? (a) 1400 (b) 1800 (c) 1600
  6. 6.Best estimate of 44 × 96? (a) 40000 (b) 400 (c) 4000
  7. 7.Best estimate of 73 × 16? (a) 14000 (b) 140 (c) 1400
  8. 8.Best estimate of 36 × 47? (a) 200 (b) 20000 (c) 2000
  9. 9.Best estimate of 13 × 19? (a) 2000 (b) 200 (c) 20
  10. 10.Best estimate of 66 × 72? (a) 4900 (b) 490 (c) 49000
  11. 11.Best estimate of 26 × 59? (a) 180 (b) 1800 (c) 18000
  12. 12.Best estimate of 19 × 50? (a) 100 (b) 1000 (c) 10000
  13. 13.Best estimate of 27 × 53? (a) 150 (b) 1500 (c) 15000
  14. 14.Best estimate of 314 + 274? (a) 600 (b) 400 (c) 800
  15. 15.Best estimate of 560 + 246? (a) 800 (b) 1000 (c) 600
  16. 16.Best estimate of 92 × 36? (a) 3600 (b) 36000 (c) 360
  17. 17.Best estimate of 166 + 161? (a) 600 (b) 400 (c) 200
  18. 18.Best estimate of 657 + 212? (a) 1100 (b) 700 (c) 900
  19. 19.Best estimate of 231 + 417? (a) 400 (b) 600 (c) 800
  20. 20.Best estimate of 298 + 201? (a) 700 (b) 500 (c) 300
  21. 21.Best estimate of 81 × 49? (a) 40000 (b) 4000 (c) 400
  22. 22.Best estimate of 351 + 178? (a) 600 (b) 800 (c) 400
  23. 23.Best estimate of 138 + 171? (a) 100 (b) 500 (c) 300
  24. 24.Best estimate of 69 × 71? (a) 4900 (b) 49000 (c) 490
  25. 25.Best estimate of 36 × 87? (a) 360 (b) 36000 (c) 3600
  26. 26.Best estimate of 20 × 98? (a) 2000 (b) 20000 (c) 200
  27. 27.Best estimate of 436 + 306? (a) 700 (b) 900 (c) 500
  28. 28.Best estimate of 31 × 78? (a) 24000 (b) 240 (c) 2400
  29. 29.Best estimate of 47 × 50? (a) 250 (b) 25000 (c) 2500
  30. 30.Best estimate of 93 × 93? (a) 8100 (b) 81000 (c) 810
  31. 31.Best estimate of 628 + 237? (a) 800 (b) 600 (c) 1000
  32. 32.Best estimate of 819 + 800? (a) 1400 (b) 1600 (c) 1800
  33. 33.Best estimate of 857 + 644? (a) 1500 (b) 1300 (c) 1700
  34. 34.Best estimate of 24 × 37? (a) 80 (b) 8000 (c) 800
  35. 35.Best estimate of 96 × 88? (a) 900 (b) 90000 (c) 9000
  36. 36.Best estimate of 80 × 23? (a) 1600 (b) 16000 (c) 160
  37. 37.Best estimate of 205 + 162? (a) 200 (b) 400 (c) 600
  38. 38.Best estimate of 86 × 93? (a) 81000 (b) 810 (c) 8100
  39. 39.Best estimate of 580 + 858? (a) 1300 (b) 1700 (c) 1500
  40. 40.Best estimate of 78 × 42? (a) 320 (b) 32000 (c) 3200

Answer key

  1. 4500
  2. 800
  3. 800
  4. 1600
  5. 1600
  6. 4000
  7. 1400
  8. 2000
  9. 200
  10. 4900
  11. 1800
  12. 1000
  13. 1500
  14. 600
  15. 800
  16. 3600
  17. 400
  18. 900
  19. 600
  20. 500
  21. 4000
  22. 600
  23. 300
  24. 4900
  25. 3600
  26. 2000
  27. 700
  28. 2400
  29. 2500
  30. 8100
  31. 800
  32. 1600
  33. 1500
  34. 800
  35. 9000
  36. 1600
  37. 400
  38. 8100
  39. 1500
  40. 3200

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