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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 381 · 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.√48 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.8 (d) 7.0
  2. 2.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.9 (d) 4.8
  3. 3.Best estimate of 3421 ÷ 86? (a) 380 (b) 3800 (c) 38
  4. 4.Best estimate of 2181 ÷ 59? (a) 360 (b) 3600 (c) 36
  5. 5.√58 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.3 (d) 7.6
  6. 6.Best estimate of 2783 ÷ 37? (a) 7000 (b) 70 (c) 700
  7. 7.√28 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.3
  8. 8.√21 to 1 decimal place? (a) 4.4 (b) 4.7 (c) 4.6 (d) 4.5
  9. 9.Best estimate of 2810 ÷ 39? (a) 7000 (b) 70 (c) 700
  10. 10.√20 to 1 decimal place? (a) 4.8 (b) 4.5 (c) 4.7 (d) 4.6
  11. 11.Best estimate of 530 ÷ 38? (a) 130 (b) 1300 (c) 13
  12. 12.√50 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 7.2 (d) 7.3
  13. 13.√27 to 1 decimal place? (a) 5.0 (b) 5.3 (c) 5.1 (d) 5.2
  14. 14.Best estimate of 1818 ÷ 31? (a) 610 (b) 6100 (c) 61
  15. 15.√87 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.4 (d) 9.3
  16. 16.√69 to 1 decimal place? (a) 8.0 (b) 8.3 (c) 8.2 (d) 8.1
  17. 17.Best estimate of 288 ÷ 21? (a) 14 (b) 140 (c) 1400
  18. 18.Best estimate of 3019 ÷ 32? (a) 1010 (b) 101 (c) 10100
  19. 19.√76 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.6 (d) 8.9
  20. 20.Best estimate of 7133 ÷ 77? (a) 8900 (b) 890 (c) 89
  21. 21.√78 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 9.0 (d) 8.8
  22. 22.Best estimate of 2320 ÷ 26? (a) 7700 (b) 770 (c) 77
  23. 23.Best estimate of 854 ÷ 22? (a) 43 (b) 4300 (c) 430
  24. 24.√35 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 5.9 (d) 6.1
  25. 25.Best estimate of 1073 ÷ 24? (a) 54 (b) 540 (c) 5400
  26. 26.√56 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.7 (d) 7.5
  27. 27.Best estimate of 3195 ÷ 84? (a) 40 (b) 400 (c) 4000
  28. 28.Best estimate of 453 ÷ 21? (a) 2300 (b) 230 (c) 23
  29. 29.Best estimate of 1660 ÷ 31? (a) 55 (b) 550 (c) 5500
  30. 30.Best estimate of 4795 ÷ 57? (a) 800 (b) 8000 (c) 80
  31. 31.Best estimate of 1524 ÷ 33? (a) 510 (b) 5100 (c) 51
  32. 32.√61 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 8.0 (d) 7.8
  33. 33.Best estimate of 2231 ÷ 64? (a) 37 (b) 3700 (c) 370
  34. 34.√30 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.5 (d) 5.4
  35. 35.Best estimate of 5312 ÷ 64? (a) 890 (b) 8900 (c) 89
  36. 36.Best estimate of 1990 ÷ 34? (a) 6600 (b) 660 (c) 66
  37. 37.Best estimate of 2180 ÷ 51? (a) 440 (b) 44 (c) 4400
  38. 38.Best estimate of 1341 ÷ 49? (a) 2700 (b) 27 (c) 270
  39. 39.Best estimate of 2051 ÷ 56? (a) 3400 (b) 34 (c) 340
  40. 40.√24 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 5.1 (d) 5.0

Answer key

  1. 6.9
  2. 5.1
  3. 38
  4. 36
  5. 7.6
  6. 70
  7. 5.3
  8. 4.6
  9. 70
  10. 4.5
  11. 13
  12. 7.1
  13. 5.2
  14. 61
  15. 9.3
  16. 8.3
  17. 14
  18. 101
  19. 8.7
  20. 89
  21. 8.8
  22. 77
  23. 43
  24. 5.9
  25. 54
  26. 7.5
  27. 40
  28. 23
  29. 55
  30. 80
  31. 51
  32. 7.8
  33. 37
  34. 5.5
  35. 89
  36. 66
  37. 44
  38. 27
  39. 34
  40. 4.9

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