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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 628 · 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 1686 ÷ 27? (a) 560 (b) 5600 (c) 56
  2. 2.Best estimate of 2538 ÷ 38? (a) 630 (b) 6300 (c) 63
  3. 3.Best estimate of 2413 ÷ 29? (a) 8000 (b) 800 (c) 80
  4. 4.Best estimate of 2056 ÷ 31? (a) 69 (b) 690 (c) 6900
  5. 5.Best estimate of 6900 ÷ 86? (a) 7700 (b) 770 (c) 77
  6. 6.Best estimate of 1252 ÷ 69? (a) 18 (b) 180 (c) 1800
  7. 7.√51 to 1 decimal place? (a) 7.3 (b) 7.0 (c) 7.1 (d) 7.2
  8. 8.√38 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.4 (d) 6.2
  9. 9.Best estimate of 1599 ÷ 63? (a) 270 (b) 27 (c) 2700
  10. 10.√69 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.2 (d) 8.4
  11. 11.√47 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.8 (d) 6.9
  12. 12.Best estimate of 2201 ÷ 79? (a) 2800 (b) 280 (c) 28
  13. 13.Best estimate of 3643 ÷ 38? (a) 91 (b) 9100 (c) 910
  14. 14.√72 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.5 (d) 8.4
  15. 15.Best estimate of 1686 ÷ 69? (a) 24 (b) 240 (c) 2400
  16. 16.Best estimate of 926 ÷ 73? (a) 13 (b) 130 (c) 1300
  17. 17.√43 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.4 (d) 6.6
  18. 18.√85 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.4 (d) 9.2
  19. 19.Best estimate of 4350 ÷ 74? (a) 6200 (b) 62 (c) 620
  20. 20.√90 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  21. 21.√65 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.1 (d) 8.0
  22. 22.Best estimate of 1051 ÷ 39? (a) 260 (b) 26 (c) 2600
  23. 23.Best estimate of 4029 ÷ 64? (a) 670 (b) 6700 (c) 67
  24. 24.√44 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.4 (d) 6.3
  25. 25.Best estimate of 2965 ÷ 41? (a) 740 (b) 7400 (c) 74
  26. 26.Best estimate of 4572 ÷ 53? (a) 9100 (b) 910 (c) 91
  27. 27.Best estimate of 2152 ÷ 23? (a) 1080 (b) 10800 (c) 108
  28. 28.Best estimate of 4005 ÷ 44? (a) 10000 (b) 1000 (c) 100
  29. 29.√24 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 5.0 (d) 4.9
  30. 30.Best estimate of 4014 ÷ 67? (a) 570 (b) 5700 (c) 57
  31. 31.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.4
  32. 32.Best estimate of 4327 ÷ 48? (a) 87 (b) 870 (c) 8700
  33. 33.√34 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.7 (d) 5.8
  34. 34.Best estimate of 1547 ÷ 39? (a) 3900 (b) 390 (c) 39
  35. 35.√83 to 1 decimal place? (a) 9.4 (b) 9.1 (c) 9.2 (d) 9.3
  36. 36.Best estimate of 4633 ÷ 82? (a) 58 (b) 5800 (c) 580
  37. 37.Best estimate of 862 ÷ 24? (a) 4300 (b) 430 (c) 43
  38. 38.Best estimate of 968 ÷ 62? (a) 1600 (b) 160 (c) 16
  39. 39.√88 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.2
  40. 40.Best estimate of 2651 ÷ 31? (a) 88 (b) 880 (c) 8800

Answer key

  1. 56
  2. 63
  3. 80
  4. 69
  5. 77
  6. 18
  7. 7.1
  8. 6.2
  9. 27
  10. 8.3
  11. 6.9
  12. 28
  13. 91
  14. 8.5
  15. 24
  16. 13
  17. 6.6
  18. 9.2
  19. 62
  20. 9.5
  21. 8.1
  22. 26
  23. 67
  24. 6.6
  25. 74
  26. 91
  27. 108
  28. 100
  29. 4.9
  30. 57
  31. 9.1
  32. 87
  33. 5.8
  34. 39
  35. 9.1
  36. 58
  37. 43
  38. 16
  39. 9.4
  40. 88

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