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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 9 · 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.√92 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  2. 2.Best estimate of 7990 ÷ 87? (a) 89 (b) 890 (c) 8900
  3. 3.Best estimate of 5124 ÷ 82? (a) 64 (b) 640 (c) 6400
  4. 4.Best estimate of 2352 ÷ 49? (a) 47 (b) 4700 (c) 470
  5. 5.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 9.7
  6. 6.Best estimate of 825 ÷ 53? (a) 1700 (b) 17 (c) 170
  7. 7.Best estimate of 2819 ÷ 32? (a) 9400 (b) 94 (c) 940
  8. 8.√85 to 1 decimal place? (a) 9.3 (b) 9.0 (c) 9.2 (d) 9.1
  9. 9.√65 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.1
  10. 10.Best estimate of 2973 ÷ 32? (a) 990 (b) 9900 (c) 99
  11. 11.√30 to 1 decimal place? (a) 5.2 (b) 5.5 (c) 5.3 (d) 5.4
  12. 12.√23 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.6 (d) 4.9
  13. 13.√75 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.5
  14. 14.√59 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.7 (d) 7.5
  15. 15.Best estimate of 2634 ÷ 31? (a) 88 (b) 880 (c) 8800
  16. 16.Best estimate of 3392 ÷ 61? (a) 57 (b) 5700 (c) 570
  17. 17.Best estimate of 1619 ÷ 26? (a) 5400 (b) 54 (c) 540
  18. 18.√47 to 1 decimal place? (a) 7.1 (b) 6.8 (c) 6.9 (d) 7.0
  19. 19.Best estimate of 2327 ÷ 36? (a) 580 (b) 5800 (c) 58
  20. 20.√89 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.4
  21. 21.√38 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.0
  22. 22.Best estimate of 4436 ÷ 81? (a) 550 (b) 5500 (c) 55
  23. 23.√66 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  24. 24.√77 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 9.1 (d) 8.9
  25. 25.Best estimate of 5154 ÷ 56? (a) 860 (b) 8600 (c) 86
  26. 26.Best estimate of 2553 ÷ 29? (a) 85 (b) 8500 (c) 850
  27. 27.Best estimate of 833 ÷ 28? (a) 280 (b) 28 (c) 2800
  28. 28.Best estimate of 7182 ÷ 76? (a) 900 (b) 9000 (c) 90
  29. 29.√56 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.3 (d) 7.5
  30. 30.√62 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 7.9 (d) 8.0
  31. 31.Best estimate of 2429 ÷ 31? (a) 8100 (b) 81 (c) 810
  32. 32.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.4
  33. 33.√34 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 6.0 (d) 5.8
  34. 34.Best estimate of 2890 ÷ 32? (a) 9600 (b) 96 (c) 960
  35. 35.Best estimate of 4555 ÷ 84? (a) 57 (b) 570 (c) 5700
  36. 36.Best estimate of 2446 ÷ 42? (a) 610 (b) 61 (c) 6100
  37. 37.Best estimate of 4420 ÷ 48? (a) 88 (b) 880 (c) 8800
  38. 38.Best estimate of 3592 ÷ 52? (a) 7200 (b) 72 (c) 720
  39. 39.Best estimate of 459 ÷ 21? (a) 2300 (b) 230 (c) 23
  40. 40.Best estimate of 922 ÷ 39? (a) 2300 (b) 23 (c) 230

Answer key

  1. 9.6
  2. 89
  3. 64
  4. 47
  5. 9.9
  6. 17
  7. 94
  8. 9.2
  9. 8.1
  10. 99
  11. 5.5
  12. 4.8
  13. 8.7
  14. 7.7
  15. 88
  16. 57
  17. 54
  18. 6.9
  19. 58
  20. 9.4
  21. 6.2
  22. 55
  23. 8.1
  24. 8.8
  25. 86
  26. 85
  27. 28
  28. 90
  29. 7.5
  30. 7.9
  31. 81
  32. 6.1
  33. 5.8
  34. 96
  35. 57
  36. 61
  37. 88
  38. 72
  39. 23
  40. 23

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