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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 926 · 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 2200 ÷ 48? (a) 4400 (b) 440 (c) 44
  2. 2.√28 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.4 (d) 5.3
  3. 3.√37 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.2 (d) 5.9
  4. 4.Best estimate of 1945 ÷ 67? (a) 280 (b) 28 (c) 2800
  5. 5.Best estimate of 3194 ÷ 37? (a) 80 (b) 800 (c) 8000
  6. 6.Best estimate of 2930 ÷ 59? (a) 4900 (b) 49 (c) 490
  7. 7.√80 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.8 (d) 8.6
  8. 8.√47 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  9. 9.√85 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.2 (d) 9.3
  10. 10.√43 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.4 (d) 6.6
  11. 11.√50 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.0 (d) 7.1
  12. 12.Best estimate of 341 ÷ 28? (a) 1100 (b) 11 (c) 110
  13. 13.Best estimate of 4721 ÷ 73? (a) 6700 (b) 67 (c) 670
  14. 14.√83 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 9.1 (d) 8.9
  15. 15.Best estimate of 4995 ÷ 79? (a) 620 (b) 6200 (c) 62
  16. 16.Best estimate of 999 ÷ 54? (a) 2000 (b) 200 (c) 20
  17. 17.Best estimate of 5252 ÷ 74? (a) 750 (b) 7500 (c) 75
  18. 18.√46 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.5 (d) 6.6
  19. 19.√58 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.5 (d) 7.6
  20. 20.√56 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.8
  21. 21.Best estimate of 2411 ÷ 27? (a) 800 (b) 80 (c) 8000
  22. 22.√98 to 1 decimal place? (a) 10.0 (b) 10.1 (c) 9.9 (d) 9.8
  23. 23.√55 to 1 decimal place? (a) 7.3 (b) 7.6 (c) 7.4 (d) 7.5
  24. 24.Best estimate of 2360 ÷ 34? (a) 79 (b) 790 (c) 7900
  25. 25.Best estimate of 2807 ÷ 36? (a) 7000 (b) 700 (c) 70
  26. 26.Best estimate of 6920 ÷ 83? (a) 870 (b) 8700 (c) 87
  27. 27.Best estimate of 1491 ÷ 67? (a) 21 (b) 210 (c) 2100
  28. 28.Best estimate of 4462 ÷ 89? (a) 500 (b) 5000 (c) 50
  29. 29.√48 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 6.9 (d) 7.1
  30. 30.√69 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.6 (d) 8.5
  31. 31.Best estimate of 3212 ÷ 64? (a) 54 (b) 5400 (c) 540
  32. 32.√90 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.5 (d) 9.6
  33. 33.√29 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.5 (d) 5.3
  34. 34.Best estimate of 4486 ÷ 61? (a) 750 (b) 75 (c) 7500
  35. 35.Best estimate of 3122 ÷ 39? (a) 7800 (b) 780 (c) 78
  36. 36.Best estimate of 3689 ÷ 58? (a) 610 (b) 6100 (c) 61
  37. 37.√23 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 4.6
  38. 38.Best estimate of 4800 ÷ 71? (a) 69 (b) 6900 (c) 690
  39. 39.√38 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.3 (d) 6.1
  40. 40.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5

Answer key

  1. 44
  2. 5.3
  3. 6.1
  4. 28
  5. 80
  6. 49
  7. 8.9
  8. 6.9
  9. 9.2
  10. 6.6
  11. 7.1
  12. 11
  13. 67
  14. 9.1
  15. 62
  16. 20
  17. 75
  18. 6.8
  19. 7.6
  20. 7.5
  21. 80
  22. 9.9
  23. 7.4
  24. 79
  25. 70
  26. 87
  27. 21
  28. 50
  29. 6.9
  30. 8.3
  31. 54
  32. 9.5
  33. 5.4
  34. 75
  35. 78
  36. 61
  37. 4.8
  38. 69
  39. 6.2
  40. 5.8

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