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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 331 · 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.√70 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.4
  2. 2.Best estimate of 2840 ÷ 54? (a) 570 (b) 57 (c) 5700
  3. 3.Best estimate of 1802 ÷ 28? (a) 60 (b) 600 (c) 6000
  4. 4.√21 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.3 (d) 4.6
  5. 5.Best estimate of 2376 ÷ 38? (a) 590 (b) 5900 (c) 59
  6. 6.Best estimate of 2095 ÷ 39? (a) 520 (b) 5200 (c) 52
  7. 7.Best estimate of 2185 ÷ 33? (a) 730 (b) 7300 (c) 73
  8. 8.√86 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.2 (d) 9.3
  9. 9.Best estimate of 5797 ÷ 83? (a) 720 (b) 7200 (c) 72
  10. 10.√37 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 5.8 (d) 5.9
  11. 11.Best estimate of 545 ÷ 37? (a) 14 (b) 140 (c) 1400
  12. 12.√61 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 8.0 (d) 7.9
  13. 13.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.5 (d) 5.8
  14. 14.Best estimate of 2405 ÷ 37? (a) 60 (b) 6000 (c) 600
  15. 15.Best estimate of 1206 ÷ 62? (a) 200 (b) 2000 (c) 20
  16. 16.Best estimate of 1678 ÷ 24? (a) 8400 (b) 84 (c) 840
  17. 17.√22 to 1 decimal place? (a) 4.7 (b) 4.4 (c) 4.6 (d) 4.5
  18. 18.√24 to 1 decimal place? (a) 4.9 (b) 4.6 (c) 4.7 (d) 4.8
  19. 19.Best estimate of 3072 ÷ 33? (a) 102 (b) 10200 (c) 1020
  20. 20.√76 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.5
  21. 21.Best estimate of 1168 ÷ 36? (a) 2900 (b) 290 (c) 29
  22. 22.Best estimate of 486 ÷ 32? (a) 160 (b) 16 (c) 1600
  23. 23.√96 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.9
  24. 24.√32 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.8 (d) 5.5
  25. 25.Best estimate of 1847 ÷ 34? (a) 62 (b) 6200 (c) 620
  26. 26.√69 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.2 (d) 8.4
  27. 27.Best estimate of 4442 ÷ 56? (a) 7400 (b) 740 (c) 74
  28. 28.Best estimate of 4057 ÷ 78? (a) 5100 (b) 510 (c) 51
  29. 29.√41 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.3
  30. 30.√77 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.6 (d) 8.7
  31. 31.Best estimate of 479 ÷ 34? (a) 160 (b) 16 (c) 1600
  32. 32.√83 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.3 (d) 9.1
  33. 33.Best estimate of 4210 ÷ 73? (a) 600 (b) 60 (c) 6000
  34. 34.√43 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.4 (d) 6.3
  35. 35.Best estimate of 392 ÷ 26? (a) 1300 (b) 130 (c) 13
  36. 36.Best estimate of 3704 ÷ 42? (a) 930 (b) 9300 (c) 93
  37. 37.Best estimate of 2082 ÷ 26? (a) 6900 (b) 69 (c) 690
  38. 38.Best estimate of 1519 ÷ 63? (a) 2500 (b) 25 (c) 250
  39. 39.Best estimate of 1570 ÷ 29? (a) 5200 (b) 520 (c) 52
  40. 40.Best estimate of 376 ÷ 24? (a) 190 (b) 1900 (c) 19

Answer key

  1. 8.4
  2. 57
  3. 60
  4. 4.6
  5. 59
  6. 52
  7. 73
  8. 9.3
  9. 72
  10. 6.1
  11. 14
  12. 7.8
  13. 5.8
  14. 60
  15. 20
  16. 84
  17. 4.7
  18. 4.9
  19. 102
  20. 8.7
  21. 29
  22. 16
  23. 9.8
  24. 5.7
  25. 62
  26. 8.3
  27. 74
  28. 51
  29. 6.4
  30. 8.8
  31. 16
  32. 9.1
  33. 60
  34. 6.6
  35. 13
  36. 93
  37. 69
  38. 25
  39. 52
  40. 19

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