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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 195 · 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 1894 ÷ 67? (a) 270 (b) 27 (c) 2700
  2. 2.√35 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 6.0 (d) 5.9
  3. 3.√40 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 6.3
  4. 4.Best estimate of 1778 ÷ 64? (a) 300 (b) 3000 (c) 30
  5. 5.Best estimate of 679 ÷ 28? (a) 2300 (b) 230 (c) 23
  6. 6.Best estimate of 3397 ÷ 61? (a) 5700 (b) 570 (c) 57
  7. 7.√98 to 1 decimal place? (a) 10.0 (b) 10.1 (c) 9.9 (d) 9.8
  8. 8.√26 to 1 decimal place? (a) 4.8 (b) 5.1 (c) 5.0 (d) 4.9
  9. 9.√87 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.2
  10. 10.Best estimate of 2170 ÷ 54? (a) 4300 (b) 43 (c) 430
  11. 11.√55 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.5 (d) 7.2
  12. 12.Best estimate of 898 ÷ 34? (a) 30 (b) 3000 (c) 300
  13. 13.√27 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 5.3 (d) 5.1
  14. 14.Best estimate of 4490 ÷ 83? (a) 5600 (b) 560 (c) 56
  15. 15.Best estimate of 609 ÷ 31? (a) 2000 (b) 200 (c) 20
  16. 16.Best estimate of 632 ÷ 52? (a) 130 (b) 13 (c) 1300
  17. 17.√41 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.4
  18. 18.Best estimate of 2681 ÷ 82? (a) 3400 (b) 340 (c) 34
  19. 19.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.2
  20. 20.Best estimate of 3263 ÷ 57? (a) 5400 (b) 54 (c) 540
  21. 21.Best estimate of 6144 ÷ 74? (a) 880 (b) 88 (c) 8800
  22. 22.Best estimate of 778 ÷ 58? (a) 130 (b) 1300 (c) 13
  23. 23.Best estimate of 1507 ÷ 43? (a) 380 (b) 38 (c) 3800
  24. 24.Best estimate of 878 ÷ 46? (a) 180 (b) 1800 (c) 18
  25. 25.Best estimate of 836 ÷ 22? (a) 42 (b) 4200 (c) 420
  26. 26.Best estimate of 3278 ÷ 81? (a) 41 (b) 410 (c) 4100
  27. 27.√89 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.1 (d) 9.4
  28. 28.Best estimate of 1808 ÷ 26? (a) 60 (b) 600 (c) 6000
  29. 29.Best estimate of 1088 ÷ 23? (a) 5400 (b) 540 (c) 54
  30. 30.Best estimate of 6080 ÷ 76? (a) 760 (b) 76 (c) 7600
  31. 31.Best estimate of 1748 ÷ 23? (a) 8700 (b) 87 (c) 870
  32. 32.√31 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.3 (d) 5.5
  33. 33.Best estimate of 1277 ÷ 53? (a) 2600 (b) 26 (c) 260
  34. 34.Best estimate of 5658 ÷ 89? (a) 6300 (b) 630 (c) 63
  35. 35.√71 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.6 (d) 8.7
  36. 36.Best estimate of 5121 ÷ 57? (a) 85 (b) 850 (c) 8500
  37. 37.Best estimate of 2020 ÷ 33? (a) 670 (b) 6700 (c) 67
  38. 38.Best estimate of 1082 ÷ 32? (a) 3600 (b) 360 (c) 36
  39. 39.Best estimate of 3071 ÷ 39? (a) 77 (b) 7700 (c) 770
  40. 40.Best estimate of 3000 ÷ 34? (a) 100 (b) 1000 (c) 10000

Answer key

  1. 27
  2. 5.9
  3. 6.3
  4. 30
  5. 23
  6. 57
  7. 9.9
  8. 5.1
  9. 9.3
  10. 43
  11. 7.4
  12. 30
  13. 5.2
  14. 56
  15. 20
  16. 13
  17. 6.4
  18. 34
  19. 8.3
  20. 54
  21. 88
  22. 13
  23. 38
  24. 18
  25. 42
  26. 41
  27. 9.4
  28. 60
  29. 54
  30. 76
  31. 87
  32. 5.6
  33. 26
  34. 63
  35. 8.4
  36. 85
  37. 67
  38. 36
  39. 77
  40. 100

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