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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 799 · 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 1974 ÷ 72? (a) 280 (b) 2800 (c) 28
  2. 2.Best estimate of 3070 ÷ 32? (a) 1020 (b) 10200 (c) 102
  3. 3.√84 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.5
  4. 4.Best estimate of 1464 ÷ 27? (a) 4900 (b) 49 (c) 490
  5. 5.√43 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.8 (d) 6.9
  6. 6.Best estimate of 2499 ÷ 81? (a) 3100 (b) 31 (c) 310
  7. 7.√89 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.1 (d) 9.4
  8. 8.Best estimate of 1234 ÷ 82? (a) 1500 (b) 15 (c) 150
  9. 9.Best estimate of 4270 ÷ 47? (a) 8500 (b) 850 (c) 85
  10. 10.Best estimate of 3592 ÷ 53? (a) 7200 (b) 720 (c) 72
  11. 11.√20 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.7 (d) 4.8
  12. 12.Best estimate of 1626 ÷ 39? (a) 4100 (b) 410 (c) 41
  13. 13.√37 to 1 decimal place? (a) 6.0 (b) 6.3 (c) 6.2 (d) 6.1
  14. 14.√82 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 8.9
  15. 15.√42 to 1 decimal place? (a) 6.2 (b) 6.5 (c) 6.4 (d) 6.3
  16. 16.Best estimate of 3131 ÷ 68? (a) 45 (b) 4500 (c) 450
  17. 17.Best estimate of 1702 ÷ 23? (a) 850 (b) 85 (c) 8500
  18. 18.Best estimate of 2399 ÷ 34? (a) 80 (b) 8000 (c) 800
  19. 19.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.1 (d) 5.2
  20. 20.Best estimate of 1095 ÷ 36? (a) 270 (b) 27 (c) 2700
  21. 21.Best estimate of 4148 ÷ 46? (a) 830 (b) 8300 (c) 83
  22. 22.Best estimate of 3408 ÷ 42? (a) 85 (b) 850 (c) 8500
  23. 23.Best estimate of 1030 ÷ 33? (a) 340 (b) 3400 (c) 34
  24. 24.Best estimate of 4303 ÷ 61? (a) 720 (b) 7200 (c) 72
  25. 25.Best estimate of 3651 ÷ 46? (a) 7300 (b) 730 (c) 73
  26. 26.Best estimate of 5576 ÷ 62? (a) 9300 (b) 930 (c) 93
  27. 27.Best estimate of 1084 ÷ 66? (a) 150 (b) 15 (c) 1500
  28. 28.Best estimate of 1669 ÷ 52? (a) 330 (b) 3300 (c) 33
  29. 29.√62 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 7.9 (d) 8.0
  30. 30.√44 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.4 (d) 6.7
  31. 31.Best estimate of 5536 ÷ 74? (a) 7900 (b) 79 (c) 790
  32. 32.√35 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.2 (d) 6.1
  33. 33.√47 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.7 (d) 6.9
  34. 34.Best estimate of 1021 ÷ 22? (a) 5100 (b) 51 (c) 510
  35. 35.√63 to 1 decimal place? (a) 8.2 (b) 8.0 (c) 7.9 (d) 8.1
  36. 36.Best estimate of 804 ÷ 24? (a) 40 (b) 400 (c) 4000
  37. 37.Best estimate of 286 ÷ 22? (a) 140 (b) 14 (c) 1400
  38. 38.Best estimate of 4807 ÷ 79? (a) 60 (b) 600 (c) 6000
  39. 39.Best estimate of 2174 ÷ 53? (a) 430 (b) 4300 (c) 43
  40. 40.Best estimate of 2962 ÷ 31? (a) 9900 (b) 990 (c) 99

Answer key

  1. 28
  2. 102
  3. 9.2
  4. 49
  5. 6.6
  6. 31
  7. 9.4
  8. 15
  9. 85
  10. 72
  11. 4.5
  12. 41
  13. 6.1
  14. 9.1
  15. 6.5
  16. 45
  17. 85
  18. 80
  19. 5.1
  20. 27
  21. 83
  22. 85
  23. 34
  24. 72
  25. 73
  26. 93
  27. 15
  28. 33
  29. 7.9
  30. 6.6
  31. 79
  32. 5.9
  33. 6.9
  34. 51
  35. 7.9
  36. 40
  37. 14
  38. 60
  39. 43
  40. 99

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