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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 316 · 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.√44 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.8
  2. 2.Best estimate of 1767 ÷ 32? (a) 59 (b) 590 (c) 5900
  3. 3.√26 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 5.2 (d) 5.1
  4. 4.Best estimate of 1504 ÷ 76? (a) 1900 (b) 190 (c) 19
  5. 5.Best estimate of 4029 ÷ 72? (a) 58 (b) 5800 (c) 580
  6. 6.Best estimate of 4399 ÷ 82? (a) 5500 (b) 550 (c) 55
  7. 7.√42 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.3 (d) 6.6
  8. 8.√82 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.3 (d) 9.2
  9. 9.Best estimate of 7492 ÷ 84? (a) 94 (b) 940 (c) 9400
  10. 10.√90 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.2
  11. 11.Best estimate of 4124 ÷ 89? (a) 46 (b) 460 (c) 4600
  12. 12.√23 to 1 decimal place? (a) 5.0 (b) 4.7 (c) 4.9 (d) 4.8
  13. 13.Best estimate of 3227 ÷ 42? (a) 8100 (b) 810 (c) 81
  14. 14.Best estimate of 1971 ÷ 82? (a) 25 (b) 250 (c) 2500
  15. 15.√21 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.3 (d) 4.4
  16. 16.Best estimate of 2630 ÷ 51? (a) 530 (b) 53 (c) 5300
  17. 17.Best estimate of 3434 ÷ 63? (a) 570 (b) 57 (c) 5700
  18. 18.Best estimate of 1001 ÷ 42? (a) 2500 (b) 25 (c) 250
  19. 19.Best estimate of 1893 ÷ 78? (a) 240 (b) 2400 (c) 24
  20. 20.Best estimate of 2566 ÷ 31? (a) 8600 (b) 860 (c) 86
  21. 21.√71 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.7 (d) 8.5
  22. 22.Best estimate of 1473 ÷ 46? (a) 2900 (b) 290 (c) 29
  23. 23.√32 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.7 (d) 5.6
  24. 24.Best estimate of 3087 ÷ 38? (a) 770 (b) 7700 (c) 77
  25. 25.Best estimate of 5911 ÷ 79? (a) 7400 (b) 74 (c) 740
  26. 26.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.8 (d) 9.7
  27. 27.Best estimate of 2408 ÷ 48? (a) 4800 (b) 480 (c) 48
  28. 28.Best estimate of 762 ÷ 32? (a) 25 (b) 250 (c) 2500
  29. 29.Best estimate of 5151 ÷ 73? (a) 74 (b) 740 (c) 7400
  30. 30.Best estimate of 7179 ÷ 77? (a) 9000 (b) 90 (c) 900
  31. 31.Best estimate of 2826 ÷ 68? (a) 4000 (b) 400 (c) 40
  32. 32.Best estimate of 1707 ÷ 22? (a) 850 (b) 8500 (c) 85
  33. 33.Best estimate of 4524 ÷ 88? (a) 5000 (b) 500 (c) 50
  34. 34.Best estimate of 1605 ÷ 73? (a) 2300 (b) 230 (c) 23
  35. 35.Best estimate of 802 ÷ 64? (a) 1300 (b) 13 (c) 130
  36. 36.√55 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.4
  37. 37.Best estimate of 788 ÷ 31? (a) 26 (b) 260 (c) 2600
  38. 38.Best estimate of 6610 ÷ 76? (a) 8300 (b) 83 (c) 830
  39. 39.Best estimate of 4545 ÷ 72? (a) 6500 (b) 65 (c) 650
  40. 40.Best estimate of 3376 ÷ 56? (a) 5600 (b) 56 (c) 560

Answer key

  1. 6.6
  2. 59
  3. 5.1
  4. 19
  5. 58
  6. 55
  7. 6.5
  8. 9.1
  9. 94
  10. 9.5
  11. 46
  12. 4.8
  13. 81
  14. 25
  15. 4.6
  16. 53
  17. 57
  18. 25
  19. 24
  20. 86
  21. 8.4
  22. 29
  23. 5.7
  24. 77
  25. 74
  26. 9.6
  27. 48
  28. 25
  29. 74
  30. 90
  31. 40
  32. 85
  33. 50
  34. 23
  35. 13
  36. 7.4
  37. 26
  38. 83
  39. 65
  40. 56

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