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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 780 · 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.√82 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 8.8
  2. 2.Best estimate of 1413 ÷ 63? (a) 2400 (b) 240 (c) 24
  3. 3.Best estimate of 1710 ÷ 62? (a) 290 (b) 29 (c) 2900
  4. 4.Best estimate of 636 ÷ 24? (a) 32 (b) 320 (c) 3200
  5. 5.Best estimate of 5680 ÷ 63? (a) 950 (b) 9500 (c) 95
  6. 6.Best estimate of 841 ÷ 27? (a) 2800 (b) 280 (c) 28
  7. 7.√96 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.9 (d) 9.7
  8. 8.Best estimate of 1507 ÷ 26? (a) 5000 (b) 50 (c) 500
  9. 9.√35 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 5.8 (d) 5.9
  10. 10.Best estimate of 4756 ÷ 59? (a) 790 (b) 79 (c) 7900
  11. 11.Best estimate of 1404 ÷ 56? (a) 230 (b) 23 (c) 2300
  12. 12.√43 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.6 (d) 6.7
  13. 13.√70 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.2 (d) 8.4
  14. 14.Best estimate of 3456 ÷ 66? (a) 490 (b) 49 (c) 4900
  15. 15.Best estimate of 4067 ÷ 62? (a) 68 (b) 6800 (c) 680
  16. 16.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.2 (d) 5.1
  17. 17.√55 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.6 (d) 7.3
  18. 18.√61 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.9 (d) 7.7
  19. 19.Best estimate of 1030 ÷ 27? (a) 34 (b) 340 (c) 3400
  20. 20.√42 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.6 (d) 6.8
  21. 21.√71 to 1 decimal place? (a) 8.4 (b) 8.1 (c) 8.2 (d) 8.3
  22. 22.√40 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.5
  23. 23.Best estimate of 3131 ÷ 86? (a) 35 (b) 350 (c) 3500
  24. 24.Best estimate of 7404 ÷ 86? (a) 8200 (b) 82 (c) 820
  25. 25.√52 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.5 (d) 7.2
  26. 26.√79 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 9.0
  27. 27.Best estimate of 1570 ÷ 63? (a) 26 (b) 260 (c) 2600
  28. 28.Best estimate of 1014 ÷ 56? (a) 17 (b) 1700 (c) 170
  29. 29.√21 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.7 (d) 4.5
  30. 30.Best estimate of 826 ÷ 31? (a) 280 (b) 28 (c) 2800
  31. 31.Best estimate of 1173 ÷ 29? (a) 3900 (b) 390 (c) 39
  32. 32.√63 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.9 (d) 7.6
  33. 33.Best estimate of 6074 ÷ 81? (a) 7600 (b) 76 (c) 760
  34. 34.Best estimate of 3919 ÷ 54? (a) 7800 (b) 78 (c) 780
  35. 35.Best estimate of 5330 ÷ 58? (a) 8900 (b) 890 (c) 89
  36. 36.√34 to 1 decimal place? (a) 5.8 (b) 5.5 (c) 5.7 (d) 5.6
  37. 37.√46 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.5
  38. 38.√50 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.3 (d) 7.1
  39. 39.Best estimate of 1176 ÷ 33? (a) 3900 (b) 39 (c) 390
  40. 40.Best estimate of 4159 ÷ 72? (a) 5900 (b) 59 (c) 590

Answer key

  1. 9.1
  2. 24
  3. 29
  4. 32
  5. 95
  6. 28
  7. 9.8
  8. 50
  9. 5.9
  10. 79
  11. 23
  12. 6.6
  13. 8.4
  14. 49
  15. 68
  16. 5.1
  17. 7.4
  18. 7.8
  19. 34
  20. 6.5
  21. 8.4
  22. 6.3
  23. 35
  24. 82
  25. 7.2
  26. 8.9
  27. 26
  28. 17
  29. 4.6
  30. 28
  31. 39
  32. 7.9
  33. 76
  34. 78
  35. 89
  36. 5.8
  37. 6.8
  38. 7.1
  39. 39
  40. 59

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