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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 648 · 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.√42 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.6 (d) 6.3
  2. 2.√62 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 7.9 (d) 8.0
  3. 3.Best estimate of 4408 ÷ 53? (a) 8800 (b) 88 (c) 880
  4. 4.Best estimate of 3259 ÷ 44? (a) 810 (b) 8100 (c) 81
  5. 5.Best estimate of 7063 ÷ 86? (a) 78 (b) 780 (c) 7800
  6. 6.Best estimate of 1844 ÷ 58? (a) 3100 (b) 310 (c) 31
  7. 7.√78 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.5
  8. 8.Best estimate of 3614 ÷ 61? (a) 600 (b) 6000 (c) 60
  9. 9.Best estimate of 5677 ÷ 74? (a) 8100 (b) 810 (c) 81
  10. 10.√63 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 7.9 (d) 8.0
  11. 11.Best estimate of 818 ÷ 46? (a) 16 (b) 1600 (c) 160
  12. 12.√58 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.9
  13. 13.√24 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.9 (d) 5.2
  14. 14.Best estimate of 1884 ÷ 62? (a) 3100 (b) 31 (c) 310
  15. 15.√38 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.2 (d) 6.4
  16. 16.Best estimate of 2764 ÷ 62? (a) 460 (b) 46 (c) 4600
  17. 17.Best estimate of 5348 ÷ 79? (a) 670 (b) 67 (c) 6700
  18. 18.Best estimate of 3080 ÷ 41? (a) 770 (b) 77 (c) 7700
  19. 19.Best estimate of 4974 ÷ 54? (a) 990 (b) 99 (c) 9900
  20. 20.√37 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 6.1 (d) 5.9
  21. 21.Best estimate of 1017 ÷ 31? (a) 340 (b) 3400 (c) 34
  22. 22.Best estimate of 3915 ÷ 89? (a) 44 (b) 4400 (c) 440
  23. 23.Best estimate of 703 ÷ 23? (a) 3500 (b) 35 (c) 350
  24. 24.Best estimate of 2260 ÷ 53? (a) 45 (b) 4500 (c) 450
  25. 25.Best estimate of 438 ÷ 34? (a) 150 (b) 1500 (c) 15
  26. 26.√53 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.5 (d) 7.3
  27. 27.Best estimate of 4538 ÷ 58? (a) 7600 (b) 760 (c) 76
  28. 28.√84 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.4
  29. 29.√28 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.3 (d) 5.6
  30. 30.Best estimate of 1165 ÷ 38? (a) 290 (b) 29 (c) 2900
  31. 31.√29 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.3 (d) 5.4
  32. 32.Best estimate of 2260 ÷ 52? (a) 45 (b) 4500 (c) 450
  33. 33.Best estimate of 7216 ÷ 81? (a) 90 (b) 9000 (c) 900
  34. 34.Best estimate of 1431 ÷ 23? (a) 720 (b) 72 (c) 7200
  35. 35.√80 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.9 (d) 8.8
  36. 36.Best estimate of 1533 ÷ 33? (a) 510 (b) 51 (c) 5100
  37. 37.Best estimate of 1197 ÷ 26? (a) 400 (b) 40 (c) 4000
  38. 38.√55 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.5 (d) 7.4
  39. 39.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 6.9 (d) 7.0
  40. 40.√34 to 1 decimal place? (a) 5.8 (b) 6.1 (c) 6.0 (d) 5.9

Answer key

  1. 6.5
  2. 7.9
  3. 88
  4. 81
  5. 78
  6. 31
  7. 8.8
  8. 60
  9. 81
  10. 7.9
  11. 16
  12. 7.6
  13. 4.9
  14. 31
  15. 6.2
  16. 46
  17. 67
  18. 77
  19. 99
  20. 6.1
  21. 34
  22. 44
  23. 35
  24. 45
  25. 15
  26. 7.3
  27. 76
  28. 9.2
  29. 5.3
  30. 29
  31. 5.4
  32. 45
  33. 90
  34. 72
  35. 8.9
  36. 51
  37. 40
  38. 7.4
  39. 7.1
  40. 5.8

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