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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 524 · 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 2428 ÷ 34? (a) 81 (b) 810 (c) 8100
  2. 2.√69 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.1
  3. 3.Best estimate of 2789 ÷ 76? (a) 3500 (b) 35 (c) 350
  4. 4.Best estimate of 1275 ÷ 76? (a) 16 (b) 160 (c) 1600
  5. 5.Best estimate of 1007 ÷ 27? (a) 3400 (b) 340 (c) 34
  6. 6.√98 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.6 (d) 9.8
  7. 7.Best estimate of 3497 ÷ 42? (a) 870 (b) 87 (c) 8700
  8. 8.√50 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.3 (d) 7.1
  9. 9.√38 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.1 (d) 6.3
  10. 10.√59 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.4 (d) 7.5
  11. 11.Best estimate of 3563 ÷ 46? (a) 7100 (b) 710 (c) 71
  12. 12.√20 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.6 (d) 4.3
  13. 13.√41 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.4 (d) 6.5
  14. 14.√42 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.6 (d) 6.5
  15. 15.Best estimate of 2998 ÷ 76? (a) 370 (b) 37 (c) 3700
  16. 16.Best estimate of 1713 ÷ 42? (a) 43 (b) 4300 (c) 430
  17. 17.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.2 (d) 6.1
  18. 18.√31 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.8 (d) 5.6
  19. 19.√34 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 6.0 (d) 6.1
  20. 20.Best estimate of 2902 ÷ 79? (a) 360 (b) 3600 (c) 36
  21. 21.Best estimate of 3872 ÷ 58? (a) 65 (b) 650 (c) 6500
  22. 22.Best estimate of 934 ÷ 38? (a) 23 (b) 2300 (c) 230
  23. 23.√96 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  24. 24.Best estimate of 3574 ÷ 41? (a) 89 (b) 890 (c) 8900
  25. 25.Best estimate of 7316 ÷ 89? (a) 810 (b) 8100 (c) 81
  26. 26.Best estimate of 1548 ÷ 64? (a) 26 (b) 2600 (c) 260
  27. 27.√47 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.1 (d) 7.0
  28. 28.Best estimate of 3845 ÷ 62? (a) 64 (b) 6400 (c) 640
  29. 29.Best estimate of 1925 ÷ 78? (a) 2400 (b) 240 (c) 24
  30. 30.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 10.0
  31. 31.Best estimate of 620 ÷ 49? (a) 120 (b) 12 (c) 1200
  32. 32.√79 to 1 decimal place? (a) 8.6 (b) 8.9 (c) 8.8 (d) 8.7
  33. 33.√84 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.1
  34. 34.√35 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.7 (d) 5.8
  35. 35.√62 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.8 (d) 7.7
  36. 36.Best estimate of 545 ÷ 24? (a) 2700 (b) 270 (c) 27
  37. 37.√88 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.2
  38. 38.√48 to 1 decimal place? (a) 7.1 (b) 6.8 (c) 7.0 (d) 6.9
  39. 39.Best estimate of 6458 ÷ 83? (a) 81 (b) 8100 (c) 810
  40. 40.Best estimate of 3176 ÷ 51? (a) 6400 (b) 64 (c) 640

Answer key

  1. 81
  2. 8.3
  3. 35
  4. 16
  5. 34
  6. 9.9
  7. 87
  8. 7.1
  9. 6.2
  10. 7.7
  11. 71
  12. 4.5
  13. 6.4
  14. 6.5
  15. 37
  16. 43
  17. 6.3
  18. 5.6
  19. 5.8
  20. 36
  21. 65
  22. 23
  23. 9.8
  24. 89
  25. 81
  26. 26
  27. 6.9
  28. 64
  29. 24
  30. 9.7
  31. 12
  32. 8.9
  33. 9.2
  34. 5.9
  35. 7.9
  36. 27
  37. 9.4
  38. 6.9
  39. 81
  40. 64

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