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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 980 · 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 686 ÷ 37? (a) 1700 (b) 170 (c) 17
  2. 2.Best estimate of 7146 ÷ 87? (a) 7900 (b) 790 (c) 79
  3. 3.√61 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.8
  4. 4.Best estimate of 2566 ÷ 32? (a) 8600 (b) 860 (c) 86
  5. 5.√23 to 1 decimal place? (a) 4.7 (b) 5.0 (c) 4.9 (d) 4.8
  6. 6.√69 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.5 (d) 8.3
  7. 7.√41 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.6 (d) 6.3
  8. 8.Best estimate of 2543 ÷ 42? (a) 6400 (b) 64 (c) 640
  9. 9.Best estimate of 719 ÷ 21? (a) 360 (b) 3600 (c) 36
  10. 10.√94 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.7
  11. 11.Best estimate of 1165 ÷ 26? (a) 39 (b) 390 (c) 3900
  12. 12.Best estimate of 4752 ÷ 54? (a) 950 (b) 95 (c) 9500
  13. 13.√43 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.7 (d) 6.4
  14. 14.√48 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 6.9 (d) 6.7
  15. 15.√79 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  16. 16.√28 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.3
  17. 17.Best estimate of 4872 ÷ 83? (a) 610 (b) 6100 (c) 61
  18. 18.Best estimate of 2598 ÷ 48? (a) 52 (b) 520 (c) 5200
  19. 19.Best estimate of 3344 ÷ 57? (a) 5600 (b) 560 (c) 56
  20. 20.√20 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.7 (d) 4.4
  21. 21.Best estimate of 1811 ÷ 69? (a) 260 (b) 26 (c) 2600
  22. 22.Best estimate of 2309 ÷ 31? (a) 770 (b) 7700 (c) 77
  23. 23.√22 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 4.6 (d) 4.7
  24. 24.√47 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 6.7
  25. 25.Best estimate of 1816 ÷ 51? (a) 360 (b) 3600 (c) 36
  26. 26.Best estimate of 343 ÷ 24? (a) 170 (b) 1700 (c) 17
  27. 27.Best estimate of 3840 ÷ 51? (a) 77 (b) 7700 (c) 770
  28. 28.√30 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.7 (d) 5.8
  29. 29.√84 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.0 (d) 9.2
  30. 30.√74 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.5 (d) 8.4
  31. 31.√55 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.3
  32. 32.Best estimate of 528 ÷ 32? (a) 1800 (b) 18 (c) 180
  33. 33.Best estimate of 4518 ÷ 66? (a) 65 (b) 6500 (c) 650
  34. 34.Best estimate of 3138 ÷ 51? (a) 6300 (b) 630 (c) 63
  35. 35.√34 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.6 (d) 5.8
  36. 36.√62 to 1 decimal place? (a) 8.0 (b) 7.7 (c) 7.8 (d) 7.9
  37. 37.Best estimate of 3149 ÷ 72? (a) 45 (b) 4500 (c) 450
  38. 38.Best estimate of 4839 ÷ 66? (a) 69 (b) 6900 (c) 690
  39. 39.Best estimate of 3965 ÷ 76? (a) 500 (b) 50 (c) 5000
  40. 40.√26 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.0 (d) 5.1

Answer key

  1. 17
  2. 79
  3. 7.8
  4. 86
  5. 4.8
  6. 8.3
  7. 6.4
  8. 64
  9. 36
  10. 9.7
  11. 39
  12. 95
  13. 6.6
  14. 6.9
  15. 8.9
  16. 5.3
  17. 61
  18. 52
  19. 56
  20. 4.5
  21. 26
  22. 77
  23. 4.7
  24. 6.9
  25. 36
  26. 17
  27. 77
  28. 5.5
  29. 9.2
  30. 8.6
  31. 7.4
  32. 18
  33. 65
  34. 63
  35. 5.8
  36. 7.9
  37. 45
  38. 69
  39. 50
  40. 5.1

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