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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 504 · 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 2160 ÷ 52? (a) 4300 (b) 430 (c) 43
  2. 2.√77 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.9 (d) 8.8
  3. 3.√41 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.4 (d) 6.5
  4. 4.√43 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.5 (d) 6.4
  5. 5.√96 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.8
  6. 6.√38 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.4 (d) 6.2
  7. 7.Best estimate of 2075 ÷ 24? (a) 1040 (b) 104 (c) 10400
  8. 8.√79 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 8.7
  9. 9.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 6.9 (d) 7.0
  10. 10.Best estimate of 3877 ÷ 66? (a) 55 (b) 5500 (c) 550
  11. 11.Best estimate of 4013 ÷ 89? (a) 4500 (b) 450 (c) 45
  12. 12.Best estimate of 1522 ÷ 52? (a) 3000 (b) 300 (c) 30
  13. 13.√59 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.9
  14. 14.Best estimate of 5038 ÷ 66? (a) 72 (b) 7200 (c) 720
  15. 15.√20 to 1 decimal place? (a) 4.4 (b) 4.3 (c) 4.2 (d) 4.5
  16. 16.Best estimate of 2772 ÷ 42? (a) 69 (b) 6900 (c) 690
  17. 17.√51 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.4 (d) 7.3
  18. 18.Best estimate of 2461 ÷ 26? (a) 8200 (b) 82 (c) 820
  19. 19.Best estimate of 4002 ÷ 46? (a) 8000 (b) 80 (c) 800
  20. 20.√45 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 6.6
  21. 21.√32 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.5 (d) 5.6
  22. 22.√88 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.5
  23. 23.√52 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.3 (d) 7.1
  24. 24.Best estimate of 1005 ÷ 29? (a) 340 (b) 3400 (c) 34
  25. 25.√55 to 1 decimal place? (a) 7.7 (b) 7.4 (c) 7.6 (d) 7.5
  26. 26.√22 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.9 (d) 4.6
  27. 27.Best estimate of 4332 ÷ 56? (a) 72 (b) 7200 (c) 720
  28. 28.Best estimate of 2568 ÷ 62? (a) 430 (b) 4300 (c) 43
  29. 29.Best estimate of 1047 ÷ 26? (a) 3500 (b) 350 (c) 35
  30. 30.√47 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.7 (d) 6.8
  31. 31.Best estimate of 2134 ÷ 74? (a) 30 (b) 3000 (c) 300
  32. 32.√72 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.8 (d) 8.7
  33. 33.Best estimate of 1169 ÷ 29? (a) 390 (b) 3900 (c) 39
  34. 34.Best estimate of 4977 ÷ 69? (a) 710 (b) 7100 (c) 71
  35. 35.Best estimate of 1117 ÷ 39? (a) 2800 (b) 28 (c) 280
  36. 36.√94 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.0 (d) 9.7
  37. 37.Best estimate of 2158 ÷ 42? (a) 540 (b) 54 (c) 5400
  38. 38.Best estimate of 5299 ÷ 58? (a) 880 (b) 8800 (c) 88
  39. 39.Best estimate of 5463 ÷ 67? (a) 78 (b) 7800 (c) 780
  40. 40.Best estimate of 860 ÷ 36? (a) 2200 (b) 220 (c) 22

Answer key

  1. 43
  2. 8.8
  3. 6.4
  4. 6.6
  5. 9.8
  6. 6.2
  7. 104
  8. 8.9
  9. 7.1
  10. 55
  11. 45
  12. 30
  13. 7.7
  14. 72
  15. 4.5
  16. 69
  17. 7.1
  18. 82
  19. 80
  20. 6.7
  21. 5.7
  22. 9.4
  23. 7.2
  24. 34
  25. 7.4
  26. 4.7
  27. 72
  28. 43
  29. 35
  30. 6.9
  31. 30
  32. 8.5
  33. 39
  34. 71
  35. 28
  36. 9.7
  37. 54
  38. 88
  39. 78
  40. 22

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