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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 419 · 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.√92 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.7 (d) 9.5
  2. 2.Best estimate of 2380 ÷ 68? (a) 3400 (b) 340 (c) 34
  3. 3.√22 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.8 (d) 4.9
  4. 4.√77 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 9.1
  5. 5.√44 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.6 (d) 6.8
  6. 6.√52 to 1 decimal place? (a) 6.9 (b) 7.2 (c) 7.0 (d) 7.1
  7. 7.Best estimate of 4223 ÷ 79? (a) 530 (b) 5300 (c) 53
  8. 8.Best estimate of 4294 ÷ 73? (a) 6100 (b) 61 (c) 610
  9. 9.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 5.2 (d) 4.9
  10. 10.Best estimate of 3760 ÷ 41? (a) 94 (b) 940 (c) 9400
  11. 11.Best estimate of 6183 ÷ 87? (a) 690 (b) 6900 (c) 69
  12. 12.Best estimate of 1728 ÷ 36? (a) 4300 (b) 43 (c) 430
  13. 13.√29 to 1 decimal place? (a) 5.2 (b) 5.5 (c) 5.3 (d) 5.4
  14. 14.Best estimate of 6963 ÷ 73? (a) 99 (b) 9900 (c) 990
  15. 15.Best estimate of 1554 ÷ 27? (a) 52 (b) 5200 (c) 520
  16. 16.√45 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.7 (d) 6.5
  17. 17.Best estimate of 2798 ÷ 32? (a) 930 (b) 9300 (c) 93
  18. 18.√96 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 10.1 (d) 9.8
  19. 19.√85 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.0 (d) 9.2
  20. 20.Best estimate of 2131 ÷ 88? (a) 24 (b) 2400 (c) 240
  21. 21.Best estimate of 2389 ÷ 76? (a) 30 (b) 3000 (c) 300
  22. 22.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.3
  23. 23.√67 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 8.2 (d) 8.0
  24. 24.√78 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.8 (d) 8.6
  25. 25.√59 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.9 (d) 7.6
  26. 26.√82 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.4 (d) 9.2
  27. 27.Best estimate of 4984 ÷ 56? (a) 830 (b) 83 (c) 8300
  28. 28.√74 to 1 decimal place? (a) 8.9 (b) 8.6 (c) 8.7 (d) 8.8
  29. 29.√32 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.4 (d) 5.5
  30. 30.Best estimate of 1551 ÷ 89? (a) 17 (b) 1700 (c) 170
  31. 31.Best estimate of 1269 ÷ 43? (a) 320 (b) 3200 (c) 32
  32. 32.Best estimate of 1861 ÷ 42? (a) 4700 (b) 47 (c) 470
  33. 33.√89 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.2
  34. 34.Best estimate of 2814 ÷ 66? (a) 40 (b) 400 (c) 4000
  35. 35.√69 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.1 (d) 8.2
  36. 36.Best estimate of 2767 ÷ 46? (a) 5500 (b) 55 (c) 550
  37. 37.√35 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 5.9 (d) 5.8
  38. 38.√56 to 1 decimal place? (a) 7.5 (b) 7.8 (c) 7.6 (d) 7.7
  39. 39.√98 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 9.8 (d) 10.1
  40. 40.Best estimate of 519 ÷ 37? (a) 130 (b) 1300 (c) 13

Answer key

  1. 9.6
  2. 34
  3. 4.7
  4. 8.8
  5. 6.6
  6. 7.2
  7. 53
  8. 61
  9. 5.1
  10. 94
  11. 69
  12. 43
  13. 5.4
  14. 99
  15. 52
  16. 6.7
  17. 93
  18. 9.8
  19. 9.2
  20. 24
  21. 30
  22. 9.5
  23. 8.2
  24. 8.8
  25. 7.7
  26. 9.1
  27. 83
  28. 8.6
  29. 5.7
  30. 17
  31. 32
  32. 47
  33. 9.4
  34. 40
  35. 8.3
  36. 55
  37. 5.9
  38. 7.5
  39. 9.9
  40. 13

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