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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 354 · 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.√86 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 9.3
  2. 2.Best estimate of 2822 ÷ 38? (a) 71 (b) 7100 (c) 710
  3. 3.Best estimate of 8079 ÷ 87? (a) 900 (b) 9000 (c) 90
  4. 4.Best estimate of 2776 ÷ 37? (a) 690 (b) 69 (c) 6900
  5. 5.Best estimate of 4695 ÷ 52? (a) 940 (b) 94 (c) 9400
  6. 6.√78 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 9.1
  7. 7.√40 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.2
  8. 8.√98 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.8 (d) 10.0
  9. 9.Best estimate of 464 ÷ 21? (a) 2300 (b) 23 (c) 230
  10. 10.√62 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 7.6
  11. 11.Best estimate of 3393 ÷ 46? (a) 6800 (b) 680 (c) 68
  12. 12.Best estimate of 487 ÷ 33? (a) 16 (b) 160 (c) 1600
  13. 13.Best estimate of 2770 ÷ 47? (a) 550 (b) 55 (c) 5500
  14. 14.√77 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.8
  15. 15.Best estimate of 3164 ÷ 88? (a) 3500 (b) 350 (c) 35
  16. 16.Best estimate of 6640 ÷ 89? (a) 74 (b) 7400 (c) 740
  17. 17.√65 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.0 (d) 8.3
  18. 18.√47 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.9
  19. 19.Best estimate of 3005 ÷ 52? (a) 600 (b) 60 (c) 6000
  20. 20.Best estimate of 5313 ÷ 61? (a) 8900 (b) 890 (c) 89
  21. 21.Best estimate of 1368 ÷ 78? (a) 17 (b) 170 (c) 1700
  22. 22.Best estimate of 4033 ÷ 54? (a) 8100 (b) 81 (c) 810
  23. 23.Best estimate of 2212 ÷ 72? (a) 32 (b) 320 (c) 3200
  24. 24.√34 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 5.7 (d) 5.9
  25. 25.√26 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.3 (d) 5.1
  26. 26.√94 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 9.7 (d) 9.8
  27. 27.Best estimate of 1301 ÷ 49? (a) 26 (b) 260 (c) 2600
  28. 28.Best estimate of 1665 ÷ 52? (a) 3300 (b) 33 (c) 330
  29. 29.Best estimate of 2936 ÷ 49? (a) 5900 (b) 590 (c) 59
  30. 30.Best estimate of 2052 ÷ 82? (a) 26 (b) 260 (c) 2600
  31. 31.√21 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 4.6 (d) 4.8
  32. 32.Best estimate of 2537 ÷ 82? (a) 320 (b) 3200 (c) 32
  33. 33.Best estimate of 1755 ÷ 86? (a) 200 (b) 20 (c) 2000
  34. 34.√59 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.7 (d) 7.9
  35. 35.Best estimate of 1941 ÷ 51? (a) 390 (b) 3900 (c) 39
  36. 36.Best estimate of 3163 ÷ 36? (a) 790 (b) 79 (c) 7900
  37. 37.Best estimate of 1512 ÷ 21? (a) 7600 (b) 760 (c) 76
  38. 38.Best estimate of 1660 ÷ 32? (a) 550 (b) 5500 (c) 55
  39. 39.Best estimate of 4376 ÷ 62? (a) 73 (b) 730 (c) 7300
  40. 40.√29 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.3 (d) 5.6

Answer key

  1. 9.3
  2. 71
  3. 90
  4. 69
  5. 94
  6. 8.8
  7. 6.3
  8. 9.9
  9. 23
  10. 7.9
  11. 68
  12. 16
  13. 55
  14. 8.8
  15. 35
  16. 74
  17. 8.1
  18. 6.9
  19. 60
  20. 89
  21. 17
  22. 81
  23. 32
  24. 5.8
  25. 5.1
  26. 9.7
  27. 26
  28. 33
  29. 59
  30. 26
  31. 4.6
  32. 32
  33. 20
  34. 7.7
  35. 39
  36. 79
  37. 76
  38. 55
  39. 73
  40. 5.4

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