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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 746 · 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 1667 ÷ 36? (a) 42 (b) 420 (c) 4200
  2. 2.Best estimate of 4366 ÷ 66? (a) 620 (b) 62 (c) 6200
  3. 3.Best estimate of 1027 ÷ 34? (a) 3400 (b) 34 (c) 340
  4. 4.Best estimate of 697 ÷ 26? (a) 230 (b) 2300 (c) 23
  5. 5.√40 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.0
  6. 6.√85 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.0 (d) 9.2
  7. 7.Best estimate of 970 ÷ 59? (a) 16 (b) 160 (c) 1600
  8. 8.Best estimate of 1630 ÷ 37? (a) 4100 (b) 41 (c) 410
  9. 9.Best estimate of 2410 ÷ 44? (a) 60 (b) 6000 (c) 600
  10. 10.Best estimate of 2104 ÷ 66? (a) 3000 (b) 30 (c) 300
  11. 11.√89 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.2
  12. 12.√30 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  13. 13.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.0 (d) 7.3
  14. 14.Best estimate of 6345 ÷ 88? (a) 710 (b) 7100 (c) 71
  15. 15.√87 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.4 (d) 9.5
  16. 16.√70 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.4 (d) 8.6
  17. 17.√53 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.6 (d) 7.5
  18. 18.Best estimate of 5618 ÷ 88? (a) 6200 (b) 620 (c) 62
  19. 19.√28 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.0 (d) 5.1
  20. 20.Best estimate of 5034 ÷ 54? (a) 10100 (b) 101 (c) 1010
  21. 21.Best estimate of 6283 ÷ 66? (a) 90 (b) 9000 (c) 900
  22. 22.√63 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.7 (d) 7.9
  23. 23.Best estimate of 2141 ÷ 76? (a) 270 (b) 27 (c) 2700
  24. 24.Best estimate of 4662 ÷ 59? (a) 780 (b) 7800 (c) 78
  25. 25.Best estimate of 6616 ÷ 82? (a) 8300 (b) 830 (c) 83
  26. 26.Best estimate of 3757 ÷ 66? (a) 54 (b) 5400 (c) 540
  27. 27.√94 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 10.0 (d) 9.8
  28. 28.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.1 (d) 10.0
  29. 29.Best estimate of 718 ÷ 27? (a) 24 (b) 2400 (c) 240
  30. 30.√22 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.7 (d) 4.8
  31. 31.Best estimate of 562 ÷ 21? (a) 280 (b) 28 (c) 2800
  32. 32.√74 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.5
  33. 33.Best estimate of 6552 ÷ 74? (a) 940 (b) 94 (c) 9400
  34. 34.√67 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.2 (d) 8.3
  35. 35.Best estimate of 4371 ÷ 72? (a) 62 (b) 6200 (c) 620
  36. 36.Best estimate of 2322 ÷ 66? (a) 330 (b) 33 (c) 3300
  37. 37.√69 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.4
  38. 38.Best estimate of 2774 ÷ 56? (a) 4600 (b) 46 (c) 460
  39. 39.√77 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.8 (d) 9.0
  40. 40.Best estimate of 4128 ÷ 56? (a) 6900 (b) 69 (c) 690

Answer key

  1. 42
  2. 62
  3. 34
  4. 23
  5. 6.3
  6. 9.2
  7. 16
  8. 41
  9. 60
  10. 30
  11. 9.4
  12. 5.5
  13. 7.1
  14. 71
  15. 9.3
  16. 8.4
  17. 7.3
  18. 62
  19. 5.3
  20. 101
  21. 90
  22. 7.9
  23. 27
  24. 78
  25. 83
  26. 54
  27. 9.7
  28. 9.8
  29. 24
  30. 4.7
  31. 28
  32. 8.6
  33. 94
  34. 8.2
  35. 62
  36. 33
  37. 8.3
  38. 46
  39. 8.8
  40. 69

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