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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 76 · 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 4637 ÷ 66? (a) 660 (b) 66 (c) 6600
  2. 2.√32 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.7
  3. 3.Best estimate of 1317 ÷ 82? (a) 160 (b) 1600 (c) 16
  4. 4.Best estimate of 2721 ÷ 87? (a) 30 (b) 3000 (c) 300
  5. 5.√82 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.1 (d) 9.4
  6. 6.√22 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 4.7 (d) 4.9
  7. 7.√43 to 1 decimal place? (a) 6.5 (b) 6.8 (c) 6.7 (d) 6.6
  8. 8.Best estimate of 3323 ÷ 58? (a) 550 (b) 5500 (c) 55
  9. 9.√94 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.6 (d) 9.8
  10. 10.Best estimate of 4954 ÷ 88? (a) 5500 (b) 55 (c) 550
  11. 11.Best estimate of 3402 ÷ 62? (a) 5700 (b) 57 (c) 570
  12. 12.√77 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.5 (d) 8.7
  13. 13.√53 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.3
  14. 14.Best estimate of 2340 ÷ 49? (a) 4700 (b) 470 (c) 47
  15. 15.Best estimate of 1795 ÷ 42? (a) 45 (b) 4500 (c) 450
  16. 16.Best estimate of 6576 ÷ 76? (a) 820 (b) 8200 (c) 82
  17. 17.√75 to 1 decimal place? (a) 8.4 (b) 8.7 (c) 8.6 (d) 8.5
  18. 18.Best estimate of 758 ÷ 52? (a) 15 (b) 1500 (c) 150
  19. 19.√62 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  20. 20.Best estimate of 4055 ÷ 77? (a) 5100 (b) 51 (c) 510
  21. 21.Best estimate of 3413 ÷ 36? (a) 8500 (b) 850 (c) 85
  22. 22.Best estimate of 3128 ÷ 52? (a) 630 (b) 6300 (c) 63
  23. 23.√92 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.8 (d) 9.6
  24. 24.√58 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.9 (d) 7.7
  25. 25.Best estimate of 1814 ÷ 41? (a) 450 (b) 4500 (c) 45
  26. 26.Best estimate of 3133 ÷ 82? (a) 3900 (b) 39 (c) 390
  27. 27.√24 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.9 (d) 4.8
  28. 28.√52 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.0 (d) 6.9
  29. 29.Best estimate of 1706 ÷ 46? (a) 34 (b) 340 (c) 3400
  30. 30.√55 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.4 (d) 7.3
  31. 31.Best estimate of 3715 ÷ 51? (a) 74 (b) 740 (c) 7400
  32. 32.Best estimate of 3835 ÷ 66? (a) 550 (b) 55 (c) 5500
  33. 33.Best estimate of 1120 ÷ 86? (a) 120 (b) 1200 (c) 12
  34. 34.Best estimate of 6480 ÷ 72? (a) 9300 (b) 930 (c) 93
  35. 35.Best estimate of 2811 ÷ 81? (a) 35 (b) 3500 (c) 350
  36. 36.√70 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.7 (d) 8.6
  37. 37.Best estimate of 2836 ÷ 56? (a) 470 (b) 47 (c) 4700
  38. 38.Best estimate of 3403 ÷ 82? (a) 430 (b) 4300 (c) 43
  39. 39.√21 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.5
  40. 40.√88 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.4

Answer key

  1. 66
  2. 5.7
  3. 16
  4. 30
  5. 9.1
  6. 4.7
  7. 6.6
  8. 55
  9. 9.7
  10. 55
  11. 57
  12. 8.8
  13. 7.3
  14. 47
  15. 45
  16. 82
  17. 8.7
  18. 15
  19. 7.9
  20. 51
  21. 85
  22. 63
  23. 9.6
  24. 7.6
  25. 45
  26. 39
  27. 4.9
  28. 7.2
  29. 34
  30. 7.4
  31. 74
  32. 55
  33. 12
  34. 93
  35. 35
  36. 8.4
  37. 47
  38. 43
  39. 4.6
  40. 9.4

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