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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 795 · 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 210 + 539? (a) 700 (b) 500 (c) 900
  2. 2.Best estimate of 46 × 16? (a) 10000 (b) 100 (c) 1000
  3. 3.Best estimate of 729 + 159? (a) 700 (b) 1100 (c) 900
  4. 4.Best estimate of 63 × 42? (a) 24000 (b) 2400 (c) 240
  5. 5.Best estimate of 47 × 28? (a) 150 (b) 1500 (c) 15000
  6. 6.Best estimate of 523 + 309? (a) 600 (b) 1000 (c) 800
  7. 7.Best estimate of 332 + 293? (a) 800 (b) 600 (c) 400
  8. 8.Best estimate of 435 + 273? (a) 900 (b) 500 (c) 700
  9. 9.Best estimate of 74 × 70? (a) 490 (b) 4900 (c) 49000
  10. 10.Best estimate of 274 + 541? (a) 600 (b) 1000 (c) 800
  11. 11.Best estimate of 205 + 317? (a) 700 (b) 300 (c) 500
  12. 12.Best estimate of 54 × 78? (a) 40000 (b) 4000 (c) 400
  13. 13.Best estimate of 594 + 379? (a) 1000 (b) 800 (c) 1200
  14. 14.Best estimate of 372 + 494? (a) 1100 (b) 900 (c) 700
  15. 15.Best estimate of 249 + 597? (a) 800 (b) 600 (c) 1000
  16. 16.Best estimate of 76 × 80? (a) 6400 (b) 64000 (c) 640
  17. 17.Best estimate of 67 × 21? (a) 1400 (b) 140 (c) 14000
  18. 18.Best estimate of 147 + 227? (a) 300 (b) 100 (c) 500
  19. 19.Best estimate of 265 + 479? (a) 1000 (b) 600 (c) 800
  20. 20.Best estimate of 94 × 13? (a) 9000 (b) 90 (c) 900
  21. 21.Best estimate of 614 + 131? (a) 500 (b) 700 (c) 900
  22. 22.Best estimate of 13 × 92? (a) 90 (b) 9000 (c) 900
  23. 23.Best estimate of 36 × 96? (a) 400 (b) 40000 (c) 4000
  24. 24.Best estimate of 695 + 233? (a) 900 (b) 1100 (c) 700
  25. 25.Best estimate of 633 + 314? (a) 1100 (b) 900 (c) 700
  26. 26.Best estimate of 86 × 66? (a) 6300 (b) 63000 (c) 630
  27. 27.Best estimate of 43 × 76? (a) 3200 (b) 32000 (c) 320
  28. 28.Best estimate of 178 + 451? (a) 700 (b) 900 (c) 500
  29. 29.Best estimate of 36 × 72? (a) 280 (b) 28000 (c) 2800
  30. 30.Best estimate of 310 + 390? (a) 900 (b) 500 (c) 700
  31. 31.Best estimate of 416 + 188? (a) 800 (b) 400 (c) 600
  32. 32.Best estimate of 608 + 453? (a) 900 (b) 1100 (c) 1300
  33. 33.Best estimate of 18 × 80? (a) 16000 (b) 1600 (c) 160
  34. 34.Best estimate of 644 + 849? (a) 1600 (b) 1200 (c) 1400
  35. 35.Best estimate of 44 × 36? (a) 16000 (b) 160 (c) 1600
  36. 36.Best estimate of 821 + 831? (a) 1400 (b) 1800 (c) 1600
  37. 37.Best estimate of 474 + 424? (a) 700 (b) 1100 (c) 900
  38. 38.Best estimate of 40 × 24? (a) 800 (b) 80 (c) 8000
  39. 39.Best estimate of 252 + 418? (a) 500 (b) 900 (c) 700
  40. 40.Best estimate of 368 + 315? (a) 700 (b) 500 (c) 900

Answer key

  1. 700
  2. 1000
  3. 900
  4. 2400
  5. 1500
  6. 800
  7. 600
  8. 700
  9. 4900
  10. 800
  11. 500
  12. 4000
  13. 1000
  14. 900
  15. 800
  16. 6400
  17. 1400
  18. 300
  19. 800
  20. 900
  21. 700
  22. 900
  23. 4000
  24. 900
  25. 900
  26. 6300
  27. 3200
  28. 700
  29. 2800
  30. 700
  31. 600
  32. 1100
  33. 1600
  34. 1400
  35. 1600
  36. 1600
  37. 900
  38. 800
  39. 700
  40. 700

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