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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 219 · 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 3122 ÷ 76? (a) 39 (b) 3900 (c) 390
  2. 2.√45 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.8 (d) 6.6
  3. 3.Best estimate of 7076 ÷ 74? (a) 1010 (b) 10100 (c) 101
  4. 4.√23 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 4.9 (d) 4.8
  5. 5.Best estimate of 4133 ÷ 52? (a) 83 (b) 8300 (c) 830
  6. 6.Best estimate of 1868 ÷ 64? (a) 3100 (b) 31 (c) 310
  7. 7.Best estimate of 3052 ÷ 36? (a) 76 (b) 760 (c) 7600
  8. 8.√61 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.6 (d) 7.8
  9. 9.Best estimate of 4117 ÷ 84? (a) 51 (b) 510 (c) 5100
  10. 10.Best estimate of 6019 ÷ 87? (a) 67 (b) 6700 (c) 670
  11. 11.√24 to 1 decimal place? (a) 5.1 (b) 4.8 (c) 4.9 (d) 5.0
  12. 12.Best estimate of 967 ÷ 58? (a) 160 (b) 1600 (c) 16
  13. 13.√55 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.2 (d) 7.4
  14. 14.√96 to 1 decimal place? (a) 9.7 (b) 10.0 (c) 9.9 (d) 9.8
  15. 15.√29 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.1 (d) 5.2
  16. 16.√94 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.4 (d) 9.5
  17. 17.√38 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.0
  18. 18.Best estimate of 2171 ÷ 59? (a) 3600 (b) 360 (c) 36
  19. 19.Best estimate of 3065 ÷ 72? (a) 440 (b) 4400 (c) 44
  20. 20.Best estimate of 2208 ÷ 27? (a) 740 (b) 7400 (c) 74
  21. 21.Best estimate of 1088 ÷ 26? (a) 36 (b) 360 (c) 3600
  22. 22.Best estimate of 1568 ÷ 46? (a) 3100 (b) 310 (c) 31
  23. 23.Best estimate of 1986 ÷ 22? (a) 99 (b) 990 (c) 9900
  24. 24.Best estimate of 3267 ÷ 41? (a) 82 (b) 820 (c) 8200
  25. 25.√69 to 1 decimal place? (a) 8.0 (b) 8.3 (c) 8.2 (d) 8.1
  26. 26.Best estimate of 6092 ÷ 77? (a) 7600 (b) 760 (c) 76
  27. 27.√63 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.7 (d) 8.0
  28. 28.Best estimate of 2472 ÷ 41? (a) 620 (b) 6200 (c) 62
  29. 29.Best estimate of 2787 ÷ 71? (a) 400 (b) 4000 (c) 40
  30. 30.√34 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.8 (d) 5.7
  31. 31.Best estimate of 1583 ÷ 68? (a) 23 (b) 230 (c) 2300
  32. 32.Best estimate of 2059 ÷ 42? (a) 5100 (b) 510 (c) 51
  33. 33.Best estimate of 3523 ÷ 57? (a) 59 (b) 5900 (c) 590
  34. 34.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.3 (d) 8.2
  35. 35.Best estimate of 6709 ÷ 74? (a) 96 (b) 9600 (c) 960
  36. 36.√43 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.6 (d) 6.7
  37. 37.Best estimate of 7951 ÷ 83? (a) 99 (b) 990 (c) 9900
  38. 38.Best estimate of 5040 ÷ 56? (a) 8400 (b) 840 (c) 84
  39. 39.√53 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.0
  40. 40.Best estimate of 5991 ÷ 89? (a) 67 (b) 670 (c) 6700

Answer key

  1. 39
  2. 6.7
  3. 101
  4. 4.8
  5. 83
  6. 31
  7. 76
  8. 7.8
  9. 51
  10. 67
  11. 4.9
  12. 16
  13. 7.4
  14. 9.8
  15. 5.4
  16. 9.7
  17. 6.2
  18. 36
  19. 44
  20. 74
  21. 36
  22. 31
  23. 99
  24. 82
  25. 8.3
  26. 76
  27. 7.9
  28. 62
  29. 40
  30. 5.8
  31. 23
  32. 51
  33. 59
  34. 8.1
  35. 96
  36. 6.6
  37. 99
  38. 84
  39. 7.3
  40. 67

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