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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 383 · 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 4939 ÷ 53? (a) 990 (b) 9900 (c) 99
  2. 2.√96 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.7 (d) 10.0
  3. 3.√82 to 1 decimal place? (a) 9.3 (b) 9.0 (c) 9.1 (d) 9.2
  4. 4.√89 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  5. 5.Best estimate of 3259 ÷ 42? (a) 81 (b) 810 (c) 8100
  6. 6.Best estimate of 3728 ÷ 49? (a) 750 (b) 75 (c) 7500
  7. 7.Best estimate of 5764 ÷ 78? (a) 7200 (b) 720 (c) 72
  8. 8.Best estimate of 3184 ÷ 37? (a) 800 (b) 80 (c) 8000
  9. 9.√72 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.8 (d) 8.6
  10. 10.Best estimate of 2531 ÷ 47? (a) 510 (b) 51 (c) 5100
  11. 11.Best estimate of 5053 ÷ 72? (a) 7200 (b) 720 (c) 72
  12. 12.√56 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.7
  13. 13.Best estimate of 3106 ÷ 46? (a) 620 (b) 62 (c) 6200
  14. 14.Best estimate of 5878 ÷ 81? (a) 73 (b) 7300 (c) 730
  15. 15.Best estimate of 2883 ÷ 32? (a) 9600 (b) 96 (c) 960
  16. 16.Best estimate of 8020 ÷ 88? (a) 8900 (b) 890 (c) 89
  17. 17.√70 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.4
  18. 18.√23 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.8 (d) 4.7
  19. 19.Best estimate of 2556 ÷ 27? (a) 8500 (b) 85 (c) 850
  20. 20.Best estimate of 1921 ÷ 76? (a) 2400 (b) 240 (c) 24
  21. 21.Best estimate of 758 ÷ 42? (a) 19 (b) 1900 (c) 190
  22. 22.√51 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  23. 23.√38 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.3 (d) 6.0
  24. 24.Best estimate of 2263 ÷ 46? (a) 4500 (b) 450 (c) 45
  25. 25.Best estimate of 721 ÷ 37? (a) 180 (b) 1800 (c) 18
  26. 26.√46 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.5 (d) 6.7
  27. 27.Best estimate of 2607 ÷ 32? (a) 87 (b) 8700 (c) 870
  28. 28.√44 to 1 decimal place? (a) 6.8 (b) 6.5 (c) 6.6 (d) 6.7
  29. 29.Best estimate of 3497 ÷ 62? (a) 58 (b) 580 (c) 5800
  30. 30.√78 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.9
  31. 31.√77 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.8 (d) 8.5
  32. 32.Best estimate of 5369 ÷ 61? (a) 8900 (b) 89 (c) 890
  33. 33.Best estimate of 385 ÷ 23? (a) 190 (b) 19 (c) 1900
  34. 34.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.3 (d) 9.4
  35. 35.Best estimate of 4061 ÷ 61? (a) 680 (b) 6800 (c) 68
  36. 36.Best estimate of 3239 ÷ 48? (a) 650 (b) 6500 (c) 65
  37. 37.Best estimate of 5541 ÷ 83? (a) 69 (b) 6900 (c) 690
  38. 38.Best estimate of 1778 ÷ 52? (a) 360 (b) 36 (c) 3600
  39. 39.Best estimate of 964 ÷ 26? (a) 3200 (b) 320 (c) 32
  40. 40.Best estimate of 1173 ÷ 71? (a) 170 (b) 17 (c) 1700

Answer key

  1. 99
  2. 9.8
  3. 9.1
  4. 9.4
  5. 81
  6. 75
  7. 72
  8. 80
  9. 8.5
  10. 51
  11. 72
  12. 7.5
  13. 62
  14. 73
  15. 96
  16. 89
  17. 8.4
  18. 4.8
  19. 85
  20. 24
  21. 19
  22. 7.1
  23. 6.2
  24. 45
  25. 18
  26. 6.8
  27. 87
  28. 6.6
  29. 58
  30. 8.8
  31. 8.8
  32. 89
  33. 19
  34. 9.6
  35. 68
  36. 65
  37. 69
  38. 36
  39. 32
  40. 17

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