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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 884 · 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.√94 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.8 (d) 9.6
  2. 2.√79 to 1 decimal place? (a) 8.6 (b) 8.9 (c) 8.7 (d) 8.8
  3. 3.√72 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.3 (d) 8.5
  4. 4.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.3 (d) 5.0
  5. 5.Best estimate of 4040 ÷ 72? (a) 58 (b) 580 (c) 5800
  6. 6.√47 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 6.9 (d) 7.1
  7. 7.Best estimate of 823 ÷ 23? (a) 410 (b) 4100 (c) 41
  8. 8.Best estimate of 1625 ÷ 73? (a) 2300 (b) 23 (c) 230
  9. 9.√21 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 4.7 (d) 4.6
  10. 10.Best estimate of 5208 ÷ 76? (a) 6500 (b) 650 (c) 65
  11. 11.√88 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.4 (d) 9.5
  12. 12.√75 to 1 decimal place? (a) 8.6 (b) 8.9 (c) 8.7 (d) 8.8
  13. 13.√61 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  14. 14.Best estimate of 2145 ÷ 53? (a) 43 (b) 4300 (c) 430
  15. 15.Best estimate of 1874 ÷ 34? (a) 62 (b) 620 (c) 6200
  16. 16.Best estimate of 2010 ÷ 38? (a) 50 (b) 5000 (c) 500
  17. 17.√78 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.8
  18. 18.√82 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.0
  19. 19.Best estimate of 4852 ÷ 89? (a) 5400 (b) 540 (c) 54
  20. 20.Best estimate of 2991 ÷ 36? (a) 7500 (b) 750 (c) 75
  21. 21.Best estimate of 1805 ÷ 26? (a) 60 (b) 600 (c) 6000
  22. 22.√51 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.3 (d) 7.2
  23. 23.Best estimate of 5955 ÷ 68? (a) 85 (b) 850 (c) 8500
  24. 24.Best estimate of 1361 ÷ 44? (a) 3400 (b) 34 (c) 340
  25. 25.Best estimate of 3858 ÷ 41? (a) 9600 (b) 960 (c) 96
  26. 26.Best estimate of 2871 ÷ 34? (a) 960 (b) 96 (c) 9600
  27. 27.Best estimate of 3125 ÷ 87? (a) 350 (b) 35 (c) 3500
  28. 28.√29 to 1 decimal place? (a) 5.6 (b) 5.3 (c) 5.4 (d) 5.5
  29. 29.Best estimate of 1300 ÷ 57? (a) 2200 (b) 220 (c) 22
  30. 30.√44 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  31. 31.√67 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.2
  32. 32.Best estimate of 2955 ÷ 54? (a) 59 (b) 590 (c) 5900
  33. 33.Best estimate of 1920 ÷ 32? (a) 640 (b) 6400 (c) 64
  34. 34.Best estimate of 1857 ÷ 54? (a) 37 (b) 370 (c) 3700
  35. 35.√58 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.6 (d) 7.7
  36. 36.Best estimate of 4627 ÷ 72? (a) 66 (b) 660 (c) 6600
  37. 37.√34 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.7 (d) 5.8
  38. 38.Best estimate of 1575 ÷ 23? (a) 79 (b) 790 (c) 7900
  39. 39.√84 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 8.9 (d) 9.1
  40. 40.Best estimate of 1480 ÷ 23? (a) 740 (b) 74 (c) 7400

Answer key

  1. 9.7
  2. 8.9
  3. 8.5
  4. 5.1
  5. 58
  6. 6.9
  7. 41
  8. 23
  9. 4.6
  10. 65
  11. 9.4
  12. 8.7
  13. 7.8
  14. 43
  15. 62
  16. 50
  17. 8.8
  18. 9.1
  19. 54
  20. 75
  21. 60
  22. 7.1
  23. 85
  24. 34
  25. 96
  26. 96
  27. 35
  28. 5.4
  29. 22
  30. 6.6
  31. 8.2
  32. 59
  33. 64
  34. 37
  35. 7.6
  36. 66
  37. 5.8
  38. 79
  39. 9.2
  40. 74

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