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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 925 · 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 649 + 329? (a) 1100 (b) 700 (c) 900
  2. 2.Best estimate of 469 + 201? (a) 900 (b) 500 (c) 700
  3. 3.Best estimate of 21 × 61? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 856 + 869? (a) 2000 (b) 1600 (c) 1800
  5. 5.Best estimate of 66 × 56? (a) 42000 (b) 420 (c) 4200
  6. 6.Best estimate of 225 + 152? (a) 400 (b) 200 (c) 600
  7. 7.Best estimate of 390 + 840? (a) 1000 (b) 1200 (c) 1400
  8. 8.Best estimate of 453 + 564? (a) 1300 (b) 900 (c) 1100
  9. 9.Best estimate of 468 + 399? (a) 1100 (b) 900 (c) 700
  10. 10.Best estimate of 33 × 16? (a) 60 (b) 6000 (c) 600
  11. 11.Best estimate of 51 × 29? (a) 150 (b) 1500 (c) 15000
  12. 12.Best estimate of 41 × 14? (a) 4000 (b) 400 (c) 40
  13. 13.Best estimate of 27 × 40? (a) 1200 (b) 12000 (c) 120
  14. 14.Best estimate of 86 × 23? (a) 180 (b) 18000 (c) 1800
  15. 15.Best estimate of 80 × 40? (a) 320 (b) 3200 (c) 32000
  16. 16.Best estimate of 56 × 49? (a) 30000 (b) 3000 (c) 300
  17. 17.Best estimate of 740 + 795? (a) 1500 (b) 1700 (c) 1300
  18. 18.Best estimate of 76 × 34? (a) 2400 (b) 24000 (c) 240
  19. 19.Best estimate of 44 × 62? (a) 24000 (b) 240 (c) 2400
  20. 20.Best estimate of 92 × 40? (a) 360 (b) 3600 (c) 36000
  21. 21.Best estimate of 36 × 54? (a) 200 (b) 20000 (c) 2000
  22. 22.Best estimate of 82 × 26? (a) 240 (b) 24000 (c) 2400
  23. 23.Best estimate of 863 + 851? (a) 1600 (b) 1800 (c) 2000
  24. 24.Best estimate of 432 + 766? (a) 1400 (b) 1000 (c) 1200
  25. 25.Best estimate of 76 × 36? (a) 32000 (b) 320 (c) 3200
  26. 26.Best estimate of 274 + 607? (a) 1100 (b) 700 (c) 900
  27. 27.Best estimate of 59 × 53? (a) 30000 (b) 300 (c) 3000
  28. 28.Best estimate of 69 × 42? (a) 280 (b) 2800 (c) 28000
  29. 29.Best estimate of 322 + 701? (a) 800 (b) 1000 (c) 1200
  30. 30.Best estimate of 63 × 78? (a) 48000 (b) 480 (c) 4800
  31. 31.Best estimate of 93 × 76? (a) 7200 (b) 720 (c) 72000
  32. 32.Best estimate of 736 + 481? (a) 1200 (b) 1400 (c) 1000
  33. 33.Best estimate of 33 × 51? (a) 1500 (b) 15000 (c) 150
  34. 34.Best estimate of 340 + 427? (a) 500 (b) 700 (c) 900
  35. 35.Best estimate of 46 × 31? (a) 15000 (b) 150 (c) 1500
  36. 36.Best estimate of 30 × 33? (a) 9000 (b) 900 (c) 90
  37. 37.Best estimate of 321 + 520? (a) 600 (b) 1000 (c) 800
  38. 38.Best estimate of 124 + 148? (a) 400 (b) 0 (c) 200
  39. 39.Best estimate of 153 + 547? (a) 900 (b) 500 (c) 700
  40. 40.Best estimate of 538 + 508? (a) 1000 (b) 800 (c) 1200

Answer key

  1. 900
  2. 700
  3. 1200
  4. 1800
  5. 4200
  6. 400
  7. 1200
  8. 1100
  9. 900
  10. 600
  11. 1500
  12. 400
  13. 1200
  14. 1800
  15. 3200
  16. 3000
  17. 1500
  18. 2400
  19. 2400
  20. 3600
  21. 2000
  22. 2400
  23. 1800
  24. 1200
  25. 3200
  26. 900
  27. 3000
  28. 2800
  29. 1000
  30. 4800
  31. 7200
  32. 1200
  33. 1500
  34. 700
  35. 1500
  36. 900
  37. 800
  38. 200
  39. 700
  40. 1000

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