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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 662 · 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.√77 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 9.1
  2. 2.√87 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  3. 3.Best estimate of 2324 ÷ 71? (a) 33 (b) 330 (c) 3300
  4. 4.√80 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 8.7
  5. 5.Best estimate of 4253 ÷ 52? (a) 85 (b) 8500 (c) 850
  6. 6.Best estimate of 4771 ÷ 58? (a) 80 (b) 800 (c) 8000
  7. 7.Best estimate of 4604 ÷ 68? (a) 660 (b) 6600 (c) 66
  8. 8.√29 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.4 (d) 5.3
  9. 9.Best estimate of 1840 ÷ 87? (a) 200 (b) 2000 (c) 20
  10. 10.Best estimate of 1185 ÷ 46? (a) 240 (b) 2400 (c) 24
  11. 11.√38 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.0 (d) 6.1
  12. 12.Best estimate of 1085 ÷ 36? (a) 270 (b) 27 (c) 2700
  13. 13.Best estimate of 5390 ÷ 68? (a) 7700 (b) 77 (c) 770
  14. 14.Best estimate of 3182 ÷ 42? (a) 80 (b) 800 (c) 8000
  15. 15.Best estimate of 1029 ÷ 21? (a) 51 (b) 5100 (c) 510
  16. 16.Best estimate of 584 ÷ 24? (a) 290 (b) 29 (c) 2900
  17. 17.Best estimate of 6360 ÷ 67? (a) 910 (b) 9100 (c) 91
  18. 18.Best estimate of 2828 ÷ 87? (a) 31 (b) 3100 (c) 310
  19. 19.Best estimate of 4021 ÷ 71? (a) 57 (b) 570 (c) 5700
  20. 20.√43 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.7 (d) 6.4
  21. 21.Best estimate of 997 ÷ 59? (a) 170 (b) 1700 (c) 17
  22. 22.Best estimate of 488 ÷ 29? (a) 1600 (b) 160 (c) 16
  23. 23.√61 to 1 decimal place? (a) 7.7 (b) 8.0 (c) 7.8 (d) 7.9
  24. 24.Best estimate of 798 ÷ 47? (a) 16 (b) 1600 (c) 160
  25. 25.√46 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.7 (d) 6.6
  26. 26.√58 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.3 (d) 7.5
  27. 27.Best estimate of 3971 ÷ 56? (a) 6600 (b) 660 (c) 66
  28. 28.√78 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.8
  29. 29.√75 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.7 (d) 8.6
  30. 30.Best estimate of 1483 ÷ 29? (a) 4900 (b) 490 (c) 49
  31. 31.Best estimate of 2793 ÷ 78? (a) 35 (b) 350 (c) 3500
  32. 32.Best estimate of 3993 ÷ 43? (a) 1000 (b) 100 (c) 10000
  33. 33.√55 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.6 (d) 7.5
  34. 34.√96 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 9.8 (d) 9.7
  35. 35.Best estimate of 6948 ÷ 78? (a) 870 (b) 8700 (c) 87
  36. 36.Best estimate of 3218 ÷ 62? (a) 54 (b) 5400 (c) 540
  37. 37.Best estimate of 5800 ÷ 68? (a) 8300 (b) 830 (c) 83
  38. 38.Best estimate of 2436 ÷ 42? (a) 6100 (b) 61 (c) 610
  39. 39.Best estimate of 806 ÷ 24? (a) 4000 (b) 400 (c) 40
  40. 40.Best estimate of 1554 ÷ 43? (a) 39 (b) 3900 (c) 390

Answer key

  1. 8.8
  2. 9.3
  3. 33
  4. 8.9
  5. 85
  6. 80
  7. 66
  8. 5.4
  9. 20
  10. 24
  11. 6.2
  12. 27
  13. 77
  14. 80
  15. 51
  16. 29
  17. 91
  18. 31
  19. 57
  20. 6.6
  21. 17
  22. 16
  23. 7.8
  24. 16
  25. 6.8
  26. 7.6
  27. 66
  28. 8.8
  29. 8.7
  30. 49
  31. 35
  32. 100
  33. 7.4
  34. 9.8
  35. 87
  36. 54
  37. 83
  38. 61
  39. 40
  40. 39

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