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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 348 · 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.√30 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.3 (d) 5.2
  2. 2.Best estimate of 7236 ÷ 89? (a) 80 (b) 800 (c) 8000
  3. 3.Best estimate of 754 ÷ 37? (a) 1900 (b) 19 (c) 190
  4. 4.Best estimate of 1575 ÷ 21? (a) 7900 (b) 790 (c) 79
  5. 5.Best estimate of 2318 ÷ 78? (a) 290 (b) 2900 (c) 29
  6. 6.Best estimate of 4159 ÷ 57? (a) 6900 (b) 69 (c) 690
  7. 7.Best estimate of 1155 ÷ 21? (a) 5800 (b) 58 (c) 580
  8. 8.√76 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.7 (d) 9.0
  9. 9.Best estimate of 5238 ÷ 78? (a) 650 (b) 6500 (c) 65
  10. 10.√50 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 7.1
  11. 11.Best estimate of 3759 ÷ 48? (a) 7500 (b) 750 (c) 75
  12. 12.Best estimate of 2158 ÷ 36? (a) 54 (b) 5400 (c) 540
  13. 13.Best estimate of 7095 ÷ 78? (a) 890 (b) 8900 (c) 89
  14. 14.√65 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.4
  15. 15.√37 to 1 decimal place? (a) 6.1 (b) 6.4 (c) 6.3 (d) 6.2
  16. 16.Best estimate of 1493 ÷ 33? (a) 5000 (b) 50 (c) 500
  17. 17.√34 to 1 decimal place? (a) 5.8 (b) 5.5 (c) 5.7 (d) 5.6
  18. 18.Best estimate of 1297 ÷ 87? (a) 14 (b) 1400 (c) 140
  19. 19.√56 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.3
  20. 20.√28 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.3 (d) 5.1
  21. 21.Best estimate of 1444 ÷ 59? (a) 24 (b) 240 (c) 2400
  22. 22.Best estimate of 5393 ÷ 84? (a) 6700 (b) 67 (c) 670
  23. 23.Best estimate of 2659 ÷ 41? (a) 6600 (b) 66 (c) 660
  24. 24.Best estimate of 3772 ÷ 77? (a) 470 (b) 47 (c) 4700
  25. 25.√23 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.7 (d) 4.9
  26. 26.√29 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.6 (d) 5.3
  27. 27.√42 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.5 (d) 6.7
  28. 28.√96 to 1 decimal place? (a) 10.0 (b) 10.1 (c) 9.8 (d) 9.9
  29. 29.Best estimate of 1013 ÷ 28? (a) 3400 (b) 34 (c) 340
  30. 30.√44 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.6 (d) 6.7
  31. 31.√63 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 8.1 (d) 7.9
  32. 32.Best estimate of 1599 ÷ 84? (a) 200 (b) 20 (c) 2000
  33. 33.Best estimate of 2259 ÷ 37? (a) 560 (b) 56 (c) 5600
  34. 34.√46 to 1 decimal place? (a) 6.5 (b) 6.8 (c) 6.6 (d) 6.7
  35. 35.Best estimate of 2570 ÷ 49? (a) 510 (b) 51 (c) 5100
  36. 36.Best estimate of 2002 ÷ 26? (a) 6700 (b) 67 (c) 670
  37. 37.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 10.0 (d) 9.8
  38. 38.Best estimate of 3127 ÷ 57? (a) 520 (b) 5200 (c) 52
  39. 39.Best estimate of 5594 ÷ 81? (a) 7000 (b) 70 (c) 700
  40. 40.Best estimate of 1848 ÷ 86? (a) 21 (b) 2100 (c) 210

Answer key

  1. 5.5
  2. 80
  3. 19
  4. 79
  5. 29
  6. 69
  7. 58
  8. 8.7
  9. 65
  10. 7.1
  11. 75
  12. 54
  13. 89
  14. 8.1
  15. 6.1
  16. 50
  17. 5.8
  18. 14
  19. 7.5
  20. 5.3
  21. 24
  22. 67
  23. 66
  24. 47
  25. 4.8
  26. 5.4
  27. 6.5
  28. 9.8
  29. 34
  30. 6.6
  31. 7.9
  32. 20
  33. 56
  34. 6.8
  35. 51
  36. 67
  37. 9.9
  38. 52
  39. 70
  40. 21

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