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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 229 · 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.√34 to 1 decimal place? (a) 6.0 (b) 5.7 (c) 5.9 (d) 5.8
  2. 2.Best estimate of 6038 ÷ 63? (a) 10100 (b) 101 (c) 1010
  3. 3.√30 to 1 decimal place? (a) 5.4 (b) 5.7 (c) 5.6 (d) 5.5
  4. 4.√84 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.0 (d) 9.2
  5. 5.Best estimate of 3310 ÷ 41? (a) 8300 (b) 830 (c) 83
  6. 6.Best estimate of 3041 ÷ 32? (a) 1010 (b) 101 (c) 10100
  7. 7.Best estimate of 3168 ÷ 39? (a) 790 (b) 7900 (c) 79
  8. 8.Best estimate of 4599 ÷ 68? (a) 660 (b) 66 (c) 6600
  9. 9.Best estimate of 4822 ÷ 54? (a) 960 (b) 9600 (c) 96
  10. 10.Best estimate of 6993 ÷ 88? (a) 780 (b) 7800 (c) 78
  11. 11.Best estimate of 2439 ÷ 26? (a) 81 (b) 8100 (c) 810
  12. 12.√27 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 5.1 (d) 5.3
  13. 13.√51 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.0
  14. 14.√82 to 1 decimal place? (a) 9.0 (b) 9.3 (c) 9.1 (d) 9.2
  15. 15.Best estimate of 915 ÷ 27? (a) 3100 (b) 310 (c) 31
  16. 16.Best estimate of 5879 ÷ 64? (a) 98 (b) 9800 (c) 980
  17. 17.Best estimate of 4938 ÷ 57? (a) 820 (b) 82 (c) 8200
  18. 18.Best estimate of 1445 ÷ 37? (a) 360 (b) 3600 (c) 36
  19. 19.√29 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.4 (d) 5.5
  20. 20.√87 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.2
  21. 21.√31 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.9 (d) 5.8
  22. 22.√65 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.4
  23. 23.√71 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.3 (d) 8.5
  24. 24.Best estimate of 1493 ÷ 33? (a) 5000 (b) 500 (c) 50
  25. 25.Best estimate of 1740 ÷ 28? (a) 58 (b) 5800 (c) 580
  26. 26.Best estimate of 2064 ÷ 63? (a) 340 (b) 3400 (c) 34
  27. 27.Best estimate of 2420 ÷ 26? (a) 81 (b) 810 (c) 8100
  28. 28.√45 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.8 (d) 6.6
  29. 29.√21 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.6 (d) 4.3
  30. 30.Best estimate of 7072 ÷ 86? (a) 790 (b) 79 (c) 7900
  31. 31.Best estimate of 1667 ÷ 39? (a) 4200 (b) 420 (c) 42
  32. 32.Best estimate of 1560 ÷ 68? (a) 2200 (b) 22 (c) 220
  33. 33.√58 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 7.6 (d) 7.8
  34. 34.Best estimate of 2454 ÷ 56? (a) 41 (b) 410 (c) 4100
  35. 35.Best estimate of 3430 ÷ 77? (a) 4300 (b) 430 (c) 43
  36. 36.√56 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.3 (d) 7.5
  37. 37.Best estimate of 1682 ÷ 42? (a) 4200 (b) 420 (c) 42
  38. 38.Best estimate of 3640 ÷ 68? (a) 5200 (b) 52 (c) 520
  39. 39.Best estimate of 5146 ÷ 56? (a) 8600 (b) 860 (c) 86
  40. 40.Best estimate of 2258 ÷ 61? (a) 3800 (b) 380 (c) 38

Answer key

  1. 5.8
  2. 101
  3. 5.5
  4. 9.2
  5. 83
  6. 101
  7. 79
  8. 66
  9. 96
  10. 78
  11. 81
  12. 5.2
  13. 7.1
  14. 9.1
  15. 31
  16. 98
  17. 82
  18. 36
  19. 5.4
  20. 9.3
  21. 5.6
  22. 8.1
  23. 8.4
  24. 50
  25. 58
  26. 34
  27. 81
  28. 6.7
  29. 4.6
  30. 79
  31. 42
  32. 22
  33. 7.6
  34. 41
  35. 43
  36. 7.5
  37. 42
  38. 52
  39. 86
  40. 38

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