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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 811 · 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.√76 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.7 (d) 8.5
  2. 2.Best estimate of 1088 ÷ 63? (a) 18 (b) 180 (c) 1800
  3. 3.√78 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 8.6
  4. 4.√59 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.6 (d) 7.8
  5. 5.√86 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.6 (d) 9.3
  6. 6.Best estimate of 6109 ÷ 64? (a) 102 (b) 1020 (c) 10200
  7. 7.√52 to 1 decimal place? (a) 7.1 (b) 7.4 (c) 7.2 (d) 7.3
  8. 8.Best estimate of 1225 ÷ 26? (a) 410 (b) 4100 (c) 41
  9. 9.√63 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 7.9 (d) 8.0
  10. 10.Best estimate of 3079 ÷ 36? (a) 770 (b) 7700 (c) 77
  11. 11.Best estimate of 968 ÷ 34? (a) 32 (b) 320 (c) 3200
  12. 12.Best estimate of 5440 ÷ 64? (a) 9100 (b) 910 (c) 91
  13. 13.Best estimate of 1077 ÷ 31? (a) 3600 (b) 36 (c) 360
  14. 14.Best estimate of 3222 ÷ 64? (a) 540 (b) 5400 (c) 54
  15. 15.Best estimate of 2299 ÷ 29? (a) 77 (b) 770 (c) 7700
  16. 16.Best estimate of 3037 ÷ 33? (a) 1010 (b) 10100 (c) 101
  17. 17.√89 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  18. 18.Best estimate of 4615 ÷ 59? (a) 77 (b) 7700 (c) 770
  19. 19.Best estimate of 3300 ÷ 72? (a) 470 (b) 47 (c) 4700
  20. 20.√26 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 5.1 (d) 4.9
  21. 21.Best estimate of 4849 ÷ 83? (a) 6100 (b) 61 (c) 610
  22. 22.Best estimate of 756 ÷ 43? (a) 1900 (b) 190 (c) 19
  23. 23.√71 to 1 decimal place? (a) 8.4 (b) 8.7 (c) 8.6 (d) 8.5
  24. 24.√43 to 1 decimal place? (a) 6.8 (b) 6.5 (c) 6.7 (d) 6.6
  25. 25.Best estimate of 1363 ÷ 47? (a) 2700 (b) 270 (c) 27
  26. 26.Best estimate of 2139 ÷ 37? (a) 53 (b) 530 (c) 5300
  27. 27.Best estimate of 1807 ÷ 59? (a) 3000 (b) 300 (c) 30
  28. 28.Best estimate of 1784 ÷ 23? (a) 890 (b) 89 (c) 8900
  29. 29.Best estimate of 1490 ÷ 23? (a) 750 (b) 7500 (c) 75
  30. 30.Best estimate of 1156 ÷ 41? (a) 2900 (b) 29 (c) 290
  31. 31.Best estimate of 2234 ÷ 38? (a) 5600 (b) 56 (c) 560
  32. 32.√98 to 1 decimal place? (a) 9.6 (b) 9.9 (c) 9.7 (d) 9.8
  33. 33.√27 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.4 (d) 5.1
  34. 34.√69 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.6 (d) 8.5
  35. 35.Best estimate of 2086 ÷ 48? (a) 420 (b) 42 (c) 4200
  36. 36.√31 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.5 (d) 5.6
  37. 37.Best estimate of 3741 ÷ 57? (a) 6200 (b) 620 (c) 62
  38. 38.Best estimate of 3987 ÷ 53? (a) 80 (b) 8000 (c) 800
  39. 39.Best estimate of 1721 ÷ 51? (a) 3400 (b) 34 (c) 340
  40. 40.Best estimate of 4022 ÷ 42? (a) 10100 (b) 101 (c) 1010

Answer key

  1. 8.7
  2. 18
  3. 8.8
  4. 7.7
  5. 9.3
  6. 102
  7. 7.2
  8. 41
  9. 7.9
  10. 77
  11. 32
  12. 91
  13. 36
  14. 54
  15. 77
  16. 101
  17. 9.4
  18. 77
  19. 47
  20. 5.1
  21. 61
  22. 19
  23. 8.4
  24. 6.6
  25. 27
  26. 53
  27. 30
  28. 89
  29. 75
  30. 29
  31. 56
  32. 9.9
  33. 5.2
  34. 8.3
  35. 42
  36. 5.6
  37. 62
  38. 80
  39. 34
  40. 101

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