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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 477 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 2449 ÷ 63? (a) 410 (b) 41 (c) 4100
  2. 2.√35 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 5.6 (d) 5.7
  3. 3.√96 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 10.0 (d) 9.9
  4. 4.Best estimate of 1295 ÷ 33? (a) 4300 (b) 430 (c) 43
  5. 5.√22 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.9 (d) 4.7
  6. 6.√40 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.3 (d) 6.4
  7. 7.√21 to 1 decimal place? (a) 4.4 (b) 4.6 (c) 4.3 (d) 4.5
  8. 8.Best estimate of 981 ÷ 49? (a) 20 (b) 2000 (c) 200
  9. 9.Best estimate of 1048 ÷ 31? (a) 35 (b) 350 (c) 3500
  10. 10.√26 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.4 (d) 5.2
  11. 11.√34 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 5.9 (d) 6.1
  12. 12.√72 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.6 (d) 8.5
  13. 13.Best estimate of 6794 ÷ 77? (a) 850 (b) 8500 (c) 85
  14. 14.Best estimate of 718 ÷ 39? (a) 180 (b) 1800 (c) 18
  15. 15.Best estimate of 2924 ÷ 66? (a) 420 (b) 42 (c) 4200
  16. 16.√67 to 1 decimal place? (a) 8.5 (b) 8.2 (c) 8.4 (d) 8.3
  17. 17.Best estimate of 2553 ÷ 43? (a) 64 (b) 6400 (c) 640
  18. 18.Best estimate of 3075 ÷ 71? (a) 4400 (b) 440 (c) 44
  19. 19.√71 to 1 decimal place? (a) 8.4 (b) 8.1 (c) 8.3 (d) 8.2
  20. 20.Best estimate of 2549 ÷ 58? (a) 420 (b) 4200 (c) 42
  21. 21.√59 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 7.6
  22. 22.Best estimate of 4228 ÷ 62? (a) 70 (b) 700 (c) 7000
  23. 23.Best estimate of 1190 ÷ 48? (a) 240 (b) 24 (c) 2400
  24. 24.Best estimate of 1198 ÷ 73? (a) 17 (b) 170 (c) 1700
  25. 25.√38 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.2 (d) 6.0
  26. 26.Best estimate of 2722 ÷ 46? (a) 5400 (b) 540 (c) 54
  27. 27.Best estimate of 729 ÷ 26? (a) 24 (b) 2400 (c) 240
  28. 28.Best estimate of 2766 ÷ 32? (a) 9200 (b) 920 (c) 92
  29. 29.Best estimate of 2780 ÷ 41? (a) 700 (b) 7000 (c) 70
  30. 30.Best estimate of 1297 ÷ 54? (a) 260 (b) 26 (c) 2600
  31. 31.Best estimate of 2358 ÷ 56? (a) 390 (b) 3900 (c) 39
  32. 32.Best estimate of 4703 ÷ 66? (a) 670 (b) 67 (c) 6700
  33. 33.√98 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 10.1 (d) 10.2
  34. 34.Best estimate of 3143 ÷ 34? (a) 1050 (b) 10500 (c) 105
  35. 35.√55 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.4
  36. 36.Best estimate of 3244 ÷ 57? (a) 54 (b) 5400 (c) 540
  37. 37.Best estimate of 1818 ÷ 72? (a) 260 (b) 2600 (c) 26
  38. 38.Best estimate of 1509 ÷ 33? (a) 500 (b) 5000 (c) 50
  39. 39.√46 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 7.1 (d) 6.8
  40. 40.Best estimate of 7599 ÷ 87? (a) 840 (b) 8400 (c) 84

Answer key

  1. 41
  2. 5.9
  3. 9.8
  4. 43
  5. 4.7
  6. 6.3
  7. 4.6
  8. 20
  9. 35
  10. 5.1
  11. 5.8
  12. 8.5
  13. 85
  14. 18
  15. 42
  16. 8.2
  17. 64
  18. 44
  19. 8.4
  20. 42
  21. 7.7
  22. 70
  23. 24
  24. 17
  25. 6.2
  26. 54
  27. 24
  28. 92
  29. 70
  30. 26
  31. 39
  32. 67
  33. 9.9
  34. 105
  35. 7.4
  36. 54
  37. 26
  38. 50
  39. 6.8
  40. 84

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