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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 666 · 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 1294 ÷ 37? (a) 32 (b) 320 (c) 3200
  2. 2.Best estimate of 6117 ÷ 89? (a) 6800 (b) 680 (c) 68
  3. 3.Best estimate of 1910 ÷ 38? (a) 480 (b) 4800 (c) 48
  4. 4.√84 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.4
  5. 5.Best estimate of 4289 ÷ 46? (a) 86 (b) 860 (c) 8600
  6. 6.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.2
  7. 7.√30 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.5 (d) 5.3
  8. 8.√88 to 1 decimal place? (a) 9.5 (b) 9.2 (c) 9.3 (d) 9.4
  9. 9.Best estimate of 1075 ÷ 66? (a) 150 (b) 1500 (c) 15
  10. 10.Best estimate of 5120 ÷ 64? (a) 850 (b) 8500 (c) 85
  11. 11.Best estimate of 2729 ÷ 39? (a) 6800 (b) 680 (c) 68
  12. 12.√66 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 7.9 (d) 8.0
  13. 13.Best estimate of 535 ÷ 21? (a) 270 (b) 27 (c) 2700
  14. 14.√85 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.1
  15. 15.Best estimate of 1477 ÷ 46? (a) 300 (b) 3000 (c) 30
  16. 16.Best estimate of 625 ÷ 24? (a) 31 (b) 3100 (c) 310
  17. 17.√42 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.6 (d) 6.3
  18. 18.√83 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 9.1 (d) 8.9
  19. 19.Best estimate of 3676 ÷ 78? (a) 4600 (b) 460 (c) 46
  20. 20.√63 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 7.9 (d) 8.0
  21. 21.Best estimate of 973 ÷ 31? (a) 32 (b) 320 (c) 3200
  22. 22.Best estimate of 2800 ÷ 32? (a) 930 (b) 9300 (c) 93
  23. 23.Best estimate of 763 ÷ 27? (a) 25 (b) 250 (c) 2500
  24. 24.Best estimate of 4227 ÷ 47? (a) 850 (b) 8500 (c) 85
  25. 25.Best estimate of 3253 ÷ 89? (a) 36 (b) 3600 (c) 360
  26. 26.Best estimate of 6497 ÷ 76? (a) 81 (b) 810 (c) 8100
  27. 27.Best estimate of 661 ÷ 22? (a) 330 (b) 33 (c) 3300
  28. 28.Best estimate of 2585 ÷ 32? (a) 8600 (b) 86 (c) 860
  29. 29.Best estimate of 1262 ÷ 87? (a) 1400 (b) 14 (c) 140
  30. 30.√47 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.0 (d) 7.1
  31. 31.√26 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 4.9 (d) 5.1
  32. 32.Best estimate of 2614 ÷ 32? (a) 87 (b) 870 (c) 8700
  33. 33.√24 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 5.2 (d) 4.9
  34. 34.Best estimate of 2662 ÷ 78? (a) 330 (b) 33 (c) 3300
  35. 35.Best estimate of 1605 ÷ 46? (a) 3200 (b) 32 (c) 320
  36. 36.Best estimate of 5646 ÷ 86? (a) 63 (b) 6300 (c) 630
  37. 37.Best estimate of 731 ÷ 31? (a) 240 (b) 24 (c) 2400
  38. 38.Best estimate of 3990 ÷ 81? (a) 50 (b) 5000 (c) 500
  39. 39.√35 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.0 (d) 5.8
  40. 40.Best estimate of 2702 ÷ 89? (a) 300 (b) 3000 (c) 30

Answer key

  1. 32
  2. 68
  3. 48
  4. 9.2
  5. 86
  6. 8.4
  7. 5.5
  8. 9.4
  9. 15
  10. 85
  11. 68
  12. 8.1
  13. 27
  14. 9.2
  15. 30
  16. 31
  17. 6.5
  18. 9.1
  19. 46
  20. 7.9
  21. 32
  22. 93
  23. 25
  24. 85
  25. 36
  26. 81
  27. 33
  28. 86
  29. 14
  30. 6.9
  31. 5.1
  32. 87
  33. 4.9
  34. 33
  35. 32
  36. 63
  37. 24
  38. 50
  39. 5.9
  40. 30

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