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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 249 · 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 3979 ÷ 89? (a) 4400 (b) 44 (c) 440
  2. 2.Best estimate of 4065 ÷ 52? (a) 810 (b) 8100 (c) 81
  3. 3.√82 to 1 decimal place? (a) 9.4 (b) 9.1 (c) 9.2 (d) 9.3
  4. 4.Best estimate of 6695 ÷ 89? (a) 740 (b) 74 (c) 7400
  5. 5.Best estimate of 2956 ÷ 59? (a) 490 (b) 49 (c) 4900
  6. 6.Best estimate of 5903 ÷ 79? (a) 740 (b) 74 (c) 7400
  7. 7.√90 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.5 (d) 9.8
  8. 8.Best estimate of 864 ÷ 49? (a) 17 (b) 170 (c) 1700
  9. 9.Best estimate of 6947 ÷ 87? (a) 77 (b) 770 (c) 7700
  10. 10.Best estimate of 2092 ÷ 82? (a) 2600 (b) 260 (c) 26
  11. 11.√23 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 5.0 (d) 4.8
  12. 12.√78 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.6 (d) 8.8
  13. 13.Best estimate of 2158 ÷ 24? (a) 108 (b) 1080 (c) 10800
  14. 14.Best estimate of 5588 ÷ 72? (a) 8000 (b) 800 (c) 80
  15. 15.√38 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.5 (d) 6.2
  16. 16.√32 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 6.0 (d) 5.9
  17. 17.√48 to 1 decimal place? (a) 7.0 (b) 6.7 (c) 6.8 (d) 6.9
  18. 18.Best estimate of 2636 ÷ 89? (a) 2900 (b) 29 (c) 290
  19. 19.Best estimate of 3164 ÷ 71? (a) 4500 (b) 45 (c) 450
  20. 20.√43 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.5 (d) 6.6
  21. 21.Best estimate of 4015 ÷ 66? (a) 5700 (b) 57 (c) 570
  22. 22.√92 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.9
  23. 23.√74 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.5
  24. 24.Best estimate of 4158 ÷ 82? (a) 520 (b) 52 (c) 5200
  25. 25.√20 to 1 decimal place? (a) 4.3 (b) 4.5 (c) 4.6 (d) 4.4
  26. 26.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.8 (d) 4.9
  27. 27.√41 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.6 (d) 6.3
  28. 28.√31 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.6 (d) 5.3
  29. 29.√80 to 1 decimal place? (a) 8.6 (b) 8.9 (c) 8.8 (d) 8.7
  30. 30.Best estimate of 1834 ÷ 22? (a) 9200 (b) 92 (c) 920
  31. 31.Best estimate of 1517 ÷ 56? (a) 250 (b) 2500 (c) 25
  32. 32.Best estimate of 620 ÷ 32? (a) 210 (b) 21 (c) 2100
  33. 33.√59 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.8 (d) 7.7
  34. 34.√28 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.3 (d) 5.0
  35. 35.Best estimate of 366 ÷ 27? (a) 12 (b) 1200 (c) 120
  36. 36.√35 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.8 (d) 5.7
  37. 37.√65 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.1 (d) 8.0
  38. 38.Best estimate of 1788 ÷ 87? (a) 2000 (b) 20 (c) 200
  39. 39.Best estimate of 1661 ÷ 26? (a) 550 (b) 55 (c) 5500
  40. 40.Best estimate of 4361 ÷ 46? (a) 8700 (b) 870 (c) 87

Answer key

  1. 44
  2. 81
  3. 9.1
  4. 74
  5. 49
  6. 74
  7. 9.5
  8. 17
  9. 77
  10. 26
  11. 4.8
  12. 8.8
  13. 108
  14. 80
  15. 6.2
  16. 5.7
  17. 6.9
  18. 29
  19. 45
  20. 6.6
  21. 57
  22. 9.6
  23. 8.6
  24. 52
  25. 4.5
  26. 5.1
  27. 6.4
  28. 5.6
  29. 8.9
  30. 92
  31. 25
  32. 21
  33. 7.7
  34. 5.3
  35. 12
  36. 5.9
  37. 8.1
  38. 20
  39. 55
  40. 87

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