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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 862 · 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.√40 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.0 (d) 6.1
  2. 2.√78 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.6 (d) 8.7
  3. 3.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 10.1
  4. 4.Best estimate of 2109 ÷ 46? (a) 420 (b) 42 (c) 4200
  5. 5.√45 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.9 (d) 6.6
  6. 6.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.9
  7. 7.Best estimate of 1807 ÷ 52? (a) 3600 (b) 360 (c) 36
  8. 8.√62 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.9 (d) 7.8
  9. 9.√82 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.1 (d) 9.3
  10. 10.Best estimate of 3546 ÷ 57? (a) 59 (b) 590 (c) 5900
  11. 11.√32 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.6 (d) 5.4
  12. 12.Best estimate of 6333 ÷ 72? (a) 9000 (b) 900 (c) 90
  13. 13.Best estimate of 733 ÷ 31? (a) 240 (b) 2400 (c) 24
  14. 14.Best estimate of 3902 ÷ 41? (a) 9800 (b) 980 (c) 98
  15. 15.Best estimate of 366 ÷ 21? (a) 18 (b) 180 (c) 1800
  16. 16.Best estimate of 2709 ÷ 56? (a) 450 (b) 4500 (c) 45
  17. 17.Best estimate of 1421 ÷ 23? (a) 7100 (b) 71 (c) 710
  18. 18.Best estimate of 6159 ÷ 66? (a) 880 (b) 88 (c) 8800
  19. 19.√80 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.8 (d) 9.0
  20. 20.Best estimate of 3007 ÷ 54? (a) 6000 (b) 60 (c) 600
  21. 21.√69 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.0 (d) 8.2
  22. 22.Best estimate of 2928 ÷ 44? (a) 73 (b) 7300 (c) 730
  23. 23.Best estimate of 1602 ÷ 86? (a) 18 (b) 1800 (c) 180
  24. 24.Best estimate of 652 ÷ 42? (a) 16 (b) 1600 (c) 160
  25. 25.√51 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.9 (d) 7.2
  26. 26.Best estimate of 527 ÷ 32? (a) 180 (b) 1800 (c) 18
  27. 27.Best estimate of 1943 ÷ 89? (a) 2200 (b) 22 (c) 220
  28. 28.√90 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.5 (d) 9.4
  29. 29.Best estimate of 1117 ÷ 58? (a) 1900 (b) 19 (c) 190
  30. 30.Best estimate of 756 ÷ 24? (a) 3800 (b) 38 (c) 380
  31. 31.√26 to 1 decimal place? (a) 4.9 (b) 5.2 (c) 5.1 (d) 5.0
  32. 32.√85 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 8.9
  33. 33.Best estimate of 1699 ÷ 64? (a) 280 (b) 28 (c) 2800
  34. 34.√63 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.7 (d) 7.8
  35. 35.Best estimate of 5960 ÷ 82? (a) 7500 (b) 75 (c) 750
  36. 36.Best estimate of 3111 ÷ 36? (a) 78 (b) 7800 (c) 780
  37. 37.√47 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 6.9 (d) 7.0
  38. 38.√35 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.1 (d) 6.0
  39. 39.Best estimate of 5774 ÷ 67? (a) 8200 (b) 82 (c) 820
  40. 40.Best estimate of 2603 ÷ 84? (a) 3300 (b) 33 (c) 330

Answer key

  1. 6.3
  2. 8.8
  3. 9.9
  4. 42
  5. 6.7
  6. 9.7
  7. 36
  8. 7.9
  9. 9.1
  10. 59
  11. 5.7
  12. 90
  13. 24
  14. 98
  15. 18
  16. 45
  17. 71
  18. 88
  19. 8.9
  20. 60
  21. 8.3
  22. 73
  23. 18
  24. 16
  25. 7.1
  26. 18
  27. 22
  28. 9.5
  29. 19
  30. 38
  31. 5.1
  32. 9.2
  33. 28
  34. 7.9
  35. 75
  36. 78
  37. 6.9
  38. 5.9
  39. 82
  40. 33

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