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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 3 · 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 1592 ÷ 52? (a) 320 (b) 32 (c) 3200
  2. 2.√21 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.6 (d) 4.4
  3. 3.√28 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.4
  4. 4.√83 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 8.9
  5. 5.Best estimate of 832 ÷ 36? (a) 2100 (b) 21 (c) 210
  6. 6.√92 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.8
  7. 7.Best estimate of 2738 ÷ 57? (a) 4600 (b) 460 (c) 46
  8. 8.Best estimate of 2353 ÷ 82? (a) 29 (b) 290 (c) 2900
  9. 9.Best estimate of 2519 ÷ 43? (a) 63 (b) 630 (c) 6300
  10. 10.√43 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.4 (d) 6.3
  11. 11.√63 to 1 decimal place? (a) 8.0 (b) 7.7 (c) 7.9 (d) 7.8
  12. 12.Best estimate of 4641 ÷ 77? (a) 5800 (b) 58 (c) 580
  13. 13.√34 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 6.0 (d) 5.8
  14. 14.Best estimate of 5472 ÷ 69? (a) 7800 (b) 78 (c) 780
  15. 15.Best estimate of 1650 ÷ 21? (a) 830 (b) 83 (c) 8300
  16. 16.Best estimate of 1393 ÷ 29? (a) 46 (b) 4600 (c) 460
  17. 17.√94 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 9.6
  18. 18.√52 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.3 (d) 7.2
  19. 19.√55 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.4 (d) 7.3
  20. 20.Best estimate of 3536 ÷ 59? (a) 59 (b) 5900 (c) 590
  21. 21.√98 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 9.7 (d) 9.9
  22. 22.Best estimate of 1961 ÷ 54? (a) 3900 (b) 390 (c) 39
  23. 23.Best estimate of 1317 ÷ 31? (a) 44 (b) 440 (c) 4400
  24. 24.Best estimate of 1979 ÷ 21? (a) 990 (b) 99 (c) 9900
  25. 25.Best estimate of 1753 ÷ 59? (a) 29 (b) 290 (c) 2900
  26. 26.Best estimate of 731 ÷ 52? (a) 150 (b) 1500 (c) 15
  27. 27.Best estimate of 1565 ÷ 89? (a) 1700 (b) 17 (c) 170
  28. 28.√71 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.4 (d) 8.2
  29. 29.Best estimate of 2315 ÷ 41? (a) 5800 (b) 58 (c) 580
  30. 30.√96 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 10.0 (d) 9.8
  31. 31.√66 to 1 decimal place? (a) 8.4 (b) 8.1 (c) 8.2 (d) 8.3
  32. 32.Best estimate of 3372 ÷ 84? (a) 420 (b) 42 (c) 4200
  33. 33.√44 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.6 (d) 6.8
  34. 34.Best estimate of 1719 ÷ 39? (a) 430 (b) 4300 (c) 43
  35. 35.Best estimate of 2421 ÷ 42? (a) 61 (b) 6100 (c) 610
  36. 36.Best estimate of 2458 ÷ 52? (a) 4900 (b) 49 (c) 490
  37. 37.√76 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 8.7
  38. 38.√42 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.5
  39. 39.√85 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.1
  40. 40.Best estimate of 1603 ÷ 89? (a) 1800 (b) 18 (c) 180

Answer key

  1. 32
  2. 4.6
  3. 5.3
  4. 9.1
  5. 21
  6. 9.6
  7. 46
  8. 29
  9. 63
  10. 6.6
  11. 7.9
  12. 58
  13. 5.8
  14. 78
  15. 83
  16. 46
  17. 9.7
  18. 7.2
  19. 7.4
  20. 59
  21. 9.9
  22. 39
  23. 44
  24. 99
  25. 29
  26. 15
  27. 17
  28. 8.4
  29. 58
  30. 9.8
  31. 8.1
  32. 42
  33. 6.6
  34. 43
  35. 61
  36. 49
  37. 8.7
  38. 6.5
  39. 9.2
  40. 18

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