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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 951 · 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.√72 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.5 (d) 8.7
  2. 2.Best estimate of 3926 ÷ 53? (a) 790 (b) 7900 (c) 79
  3. 3.Best estimate of 1963 ÷ 84? (a) 2500 (b) 250 (c) 25
  4. 4.Best estimate of 3716 ÷ 39? (a) 9300 (b) 93 (c) 930
  5. 5.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  6. 6.Best estimate of 465 ÷ 36? (a) 12 (b) 120 (c) 1200
  7. 7.Best estimate of 2390 ÷ 72? (a) 34 (b) 3400 (c) 340
  8. 8.√67 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.0 (d) 8.3
  9. 9.Best estimate of 4106 ÷ 56? (a) 68 (b) 680 (c) 6800
  10. 10.√20 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.4 (d) 4.3
  11. 11.Best estimate of 2529 ÷ 76? (a) 3200 (b) 320 (c) 32
  12. 12.√28 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.5 (d) 5.4
  13. 13.Best estimate of 3093 ÷ 81? (a) 39 (b) 3900 (c) 390
  14. 14.Best estimate of 3776 ÷ 56? (a) 630 (b) 6300 (c) 63
  15. 15.√40 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.3 (d) 6.6
  16. 16.Best estimate of 5967 ÷ 64? (a) 990 (b) 9900 (c) 99
  17. 17.Best estimate of 6506 ÷ 78? (a) 81 (b) 810 (c) 8100
  18. 18.Best estimate of 1537 ÷ 39? (a) 3800 (b) 38 (c) 380
  19. 19.√32 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.6 (d) 5.8
  20. 20.√82 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 9.1 (d) 8.9
  21. 21.√23 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 5.0 (d) 5.1
  22. 22.√59 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.7 (d) 7.9
  23. 23.√61 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 8.0
  24. 24.Best estimate of 2348 ÷ 26? (a) 7800 (b) 78 (c) 780
  25. 25.Best estimate of 3151 ÷ 34? (a) 1050 (b) 105 (c) 10500
  26. 26.Best estimate of 2453 ÷ 63? (a) 410 (b) 4100 (c) 41
  27. 27.√90 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.5
  28. 28.√52 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.3 (d) 7.5
  29. 29.Best estimate of 5427 ÷ 76? (a) 680 (b) 6800 (c) 68
  30. 30.Best estimate of 2268 ÷ 27? (a) 760 (b) 76 (c) 7600
  31. 31.Best estimate of 1071 ÷ 79? (a) 130 (b) 13 (c) 1300
  32. 32.Best estimate of 2359 ÷ 46? (a) 47 (b) 470 (c) 4700
  33. 33.Best estimate of 2487 ÷ 26? (a) 83 (b) 8300 (c) 830
  34. 34.√85 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.5 (d) 9.4
  35. 35.√92 to 1 decimal place? (a) 9.7 (b) 9.4 (c) 9.5 (d) 9.6
  36. 36.Best estimate of 1463 ÷ 24? (a) 73 (b) 7300 (c) 730
  37. 37.Best estimate of 960 ÷ 32? (a) 3200 (b) 320 (c) 32
  38. 38.√80 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.6 (d) 8.9
  39. 39.Best estimate of 3168 ÷ 69? (a) 45 (b) 4500 (c) 450
  40. 40.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 10.0

Answer key

  1. 8.5
  2. 79
  3. 25
  4. 93
  5. 5.8
  6. 12
  7. 34
  8. 8.2
  9. 68
  10. 4.5
  11. 32
  12. 5.3
  13. 39
  14. 63
  15. 6.3
  16. 99
  17. 81
  18. 38
  19. 5.7
  20. 9.1
  21. 4.8
  22. 7.7
  23. 7.8
  24. 78
  25. 105
  26. 41
  27. 9.5
  28. 7.2
  29. 68
  30. 76
  31. 13
  32. 47
  33. 83
  34. 9.2
  35. 9.6
  36. 73
  37. 32
  38. 8.9
  39. 45
  40. 9.7

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