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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 47 · 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 1163 ÷ 36? (a) 290 (b) 2900 (c) 29
  2. 2.√26 to 1 decimal place? (a) 5.2 (b) 4.9 (c) 5.1 (d) 5.0
  3. 3.Best estimate of 2566 ÷ 73? (a) 3700 (b) 37 (c) 370
  4. 4.Best estimate of 2510 ÷ 51? (a) 5000 (b) 50 (c) 500
  5. 5.Best estimate of 2236 ÷ 39? (a) 5600 (b) 56 (c) 560
  6. 6.√47 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 7.0 (d) 6.8
  7. 7.√78 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.7 (d) 8.9
  8. 8.Best estimate of 2136 ÷ 46? (a) 430 (b) 43 (c) 4300
  9. 9.Best estimate of 5496 ÷ 86? (a) 61 (b) 6100 (c) 610
  10. 10.Best estimate of 3552 ÷ 66? (a) 51 (b) 5100 (c) 510
  11. 11.Best estimate of 1901 ÷ 69? (a) 27 (b) 270 (c) 2700
  12. 12.√90 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.4 (d) 9.6
  13. 13.√94 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.6 (d) 9.8
  14. 14.√52 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 6.9 (d) 7.1
  15. 15.Best estimate of 727 ÷ 46? (a) 150 (b) 15 (c) 1500
  16. 16.Best estimate of 2077 ÷ 34? (a) 690 (b) 69 (c) 6900
  17. 17.Best estimate of 7001 ÷ 82? (a) 880 (b) 88 (c) 8800
  18. 18.√76 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.8 (d) 8.5
  19. 19.√29 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.3 (d) 5.4
  20. 20.Best estimate of 1658 ÷ 26? (a) 5500 (b) 55 (c) 550
  21. 21.√85 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.2
  22. 22.Best estimate of 1396 ÷ 81? (a) 1700 (b) 170 (c) 17
  23. 23.√65 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 8.1
  24. 24.Best estimate of 2878 ÷ 74? (a) 4100 (b) 410 (c) 41
  25. 25.Best estimate of 2986 ÷ 59? (a) 500 (b) 5000 (c) 50
  26. 26.√32 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 5.7 (d) 5.9
  27. 27.Best estimate of 1714 ÷ 22? (a) 86 (b) 860 (c) 8600
  28. 28.Best estimate of 1527 ÷ 57? (a) 250 (b) 25 (c) 2500
  29. 29.√40 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.3 (d) 6.4
  30. 30.Best estimate of 726 ÷ 32? (a) 2400 (b) 24 (c) 240
  31. 31.√28 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.1 (d) 5.2
  32. 32.√51 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 7.0 (d) 7.1
  33. 33.Best estimate of 1860 ÷ 23? (a) 930 (b) 93 (c) 9300
  34. 34.Best estimate of 752 ÷ 26? (a) 250 (b) 2500 (c) 25
  35. 35.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.6 (d) 9.7
  36. 36.Best estimate of 3958 ÷ 83? (a) 4900 (b) 490 (c) 49
  37. 37.Best estimate of 2258 ÷ 32? (a) 750 (b) 7500 (c) 75
  38. 38.Best estimate of 2304 ÷ 27? (a) 770 (b) 77 (c) 7700
  39. 39.√34 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.6 (d) 5.8
  40. 40.Best estimate of 1585 ÷ 72? (a) 23 (b) 230 (c) 2300

Answer key

  1. 29
  2. 5.1
  3. 37
  4. 50
  5. 56
  6. 6.9
  7. 8.8
  8. 43
  9. 61
  10. 51
  11. 27
  12. 9.5
  13. 9.7
  14. 7.2
  15. 15
  16. 69
  17. 88
  18. 8.7
  19. 5.4
  20. 55
  21. 9.2
  22. 17
  23. 8.1
  24. 41
  25. 50
  26. 5.7
  27. 86
  28. 25
  29. 6.3
  30. 24
  31. 5.3
  32. 7.1
  33. 93
  34. 25
  35. 9.9
  36. 49
  37. 75
  38. 77
  39. 5.8
  40. 23

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