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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 825 · 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 2304 ÷ 57? (a) 3800 (b) 380 (c) 38
  2. 2.√34 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.8 (d) 5.7
  3. 3.√92 to 1 decimal place? (a) 9.5 (b) 9.8 (c) 9.7 (d) 9.6
  4. 4.√83 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.4 (d) 9.3
  5. 5.Best estimate of 4400 ÷ 58? (a) 7300 (b) 730 (c) 73
  6. 6.Best estimate of 3181 ÷ 39? (a) 800 (b) 80 (c) 8000
  7. 7.Best estimate of 1111 ÷ 43? (a) 2800 (b) 28 (c) 280
  8. 8.Best estimate of 3780 ÷ 42? (a) 9500 (b) 95 (c) 950
  9. 9.Best estimate of 1126 ÷ 22? (a) 5600 (b) 56 (c) 560
  10. 10.√70 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.6
  11. 11.Best estimate of 1227 ÷ 46? (a) 25 (b) 2500 (c) 250
  12. 12.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.4
  13. 13.Best estimate of 6509 ÷ 81? (a) 810 (b) 8100 (c) 81
  14. 14.Best estimate of 1875 ÷ 71? (a) 27 (b) 270 (c) 2700
  15. 15.Best estimate of 1003 ÷ 21? (a) 50 (b) 5000 (c) 500
  16. 16.Best estimate of 611 ÷ 38? (a) 150 (b) 1500 (c) 15
  17. 17.Best estimate of 3862 ÷ 83? (a) 4800 (b) 48 (c) 480
  18. 18.√40 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.4
  19. 19.Best estimate of 5746 ÷ 61? (a) 960 (b) 9600 (c) 96
  20. 20.√85 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 9.2
  21. 21.Best estimate of 7596 ÷ 87? (a) 84 (b) 8400 (c) 840
  22. 22.√42 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.5
  23. 23.Best estimate of 2180 ÷ 29? (a) 73 (b) 730 (c) 7300
  24. 24.√48 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 6.8 (d) 7.0
  25. 25.√74 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.8 (d) 8.6
  26. 26.Best estimate of 3358 ÷ 37? (a) 84 (b) 8400 (c) 840
  27. 27.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.3
  28. 28.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.9 (d) 4.8
  29. 29.√80 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.1 (d) 9.0
  30. 30.√75 to 1 decimal place? (a) 8.8 (b) 8.5 (c) 8.6 (d) 8.7
  31. 31.Best estimate of 2653 ÷ 53? (a) 5300 (b) 53 (c) 530
  32. 32.Best estimate of 3910 ÷ 72? (a) 56 (b) 560 (c) 5600
  33. 33.Best estimate of 6823 ÷ 77? (a) 85 (b) 8500 (c) 850
  34. 34.Best estimate of 5053 ÷ 58? (a) 840 (b) 8400 (c) 84
  35. 35.Best estimate of 1303 ÷ 21? (a) 650 (b) 65 (c) 6500
  36. 36.Best estimate of 1533 ÷ 57? (a) 26 (b) 260 (c) 2600
  37. 37.Best estimate of 1974 ÷ 31? (a) 660 (b) 66 (c) 6600
  38. 38.Best estimate of 2572 ÷ 73? (a) 3700 (b) 370 (c) 37
  39. 39.Best estimate of 3339 ÷ 46? (a) 670 (b) 6700 (c) 67
  40. 40.Best estimate of 2718 ÷ 86? (a) 30 (b) 3000 (c) 300

Answer key

  1. 38
  2. 5.8
  3. 9.6
  4. 9.1
  5. 73
  6. 80
  7. 28
  8. 95
  9. 56
  10. 8.4
  11. 25
  12. 6.1
  13. 81
  14. 27
  15. 50
  16. 15
  17. 48
  18. 6.3
  19. 96
  20. 9.2
  21. 84
  22. 6.5
  23. 73
  24. 6.9
  25. 8.6
  26. 84
  27. 7.6
  28. 5.1
  29. 8.9
  30. 8.7
  31. 53
  32. 56
  33. 85
  34. 84
  35. 65
  36. 26
  37. 66
  38. 37
  39. 67
  40. 30

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