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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 210 · 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 3410 ÷ 38? (a) 8500 (b) 850 (c) 85
  2. 2.Best estimate of 2017 ÷ 61? (a) 3400 (b) 340 (c) 34
  3. 3.√29 to 1 decimal place? (a) 5.1 (b) 5.4 (c) 5.3 (d) 5.2
  4. 4.Best estimate of 1353 ÷ 32? (a) 4500 (b) 450 (c) 45
  5. 5.√66 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 8.3
  6. 6.Best estimate of 1503 ÷ 51? (a) 300 (b) 3000 (c) 30
  7. 7.√89 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.3 (d) 9.5
  8. 8.Best estimate of 3270 ÷ 38? (a) 820 (b) 8200 (c) 82
  9. 9.Best estimate of 3868 ÷ 79? (a) 480 (b) 48 (c) 4800
  10. 10.Best estimate of 5132 ÷ 82? (a) 6400 (b) 640 (c) 64
  11. 11.Best estimate of 1054 ÷ 78? (a) 130 (b) 1300 (c) 13
  12. 12.√35 to 1 decimal place? (a) 5.9 (b) 5.8 (c) 6.0 (d) 5.7
  13. 13.Best estimate of 1674 ÷ 69? (a) 240 (b) 2400 (c) 24
  14. 14.Best estimate of 2283 ÷ 82? (a) 2900 (b) 29 (c) 290
  15. 15.√71 to 1 decimal place? (a) 8.5 (b) 8.2 (c) 8.4 (d) 8.3
  16. 16.√52 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.0
  17. 17.Best estimate of 2238 ÷ 28? (a) 7500 (b) 75 (c) 750
  18. 18.√55 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.5 (d) 7.4
  19. 19.Best estimate of 7340 ÷ 81? (a) 9200 (b) 920 (c) 92
  20. 20.√22 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.7 (d) 4.5
  21. 21.√74 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.8
  22. 22.Best estimate of 3351 ÷ 49? (a) 67 (b) 670 (c) 6700
  23. 23.Best estimate of 1792 ÷ 78? (a) 2200 (b) 220 (c) 22
  24. 24.Best estimate of 740 ÷ 46? (a) 150 (b) 1500 (c) 15
  25. 25.√80 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 8.6
  26. 26.Best estimate of 3176 ÷ 37? (a) 79 (b) 790 (c) 7900
  27. 27.Best estimate of 4644 ÷ 86? (a) 52 (b) 5200 (c) 520
  28. 28.Best estimate of 1470 ÷ 74? (a) 210 (b) 2100 (c) 21
  29. 29.√27 to 1 decimal place? (a) 5.1 (b) 5.4 (c) 5.2 (d) 5.3
  30. 30.Best estimate of 6008 ÷ 63? (a) 1000 (b) 100 (c) 10000
  31. 31.√23 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.9 (d) 5.0
  32. 32.Best estimate of 1211 ÷ 89? (a) 130 (b) 1300 (c) 13
  33. 33.Best estimate of 3392 ÷ 62? (a) 570 (b) 57 (c) 5700
  34. 34.Best estimate of 6425 ÷ 72? (a) 920 (b) 9200 (c) 92
  35. 35.Best estimate of 1394 ÷ 63? (a) 230 (b) 23 (c) 2300
  36. 36.Best estimate of 746 ÷ 49? (a) 150 (b) 15 (c) 1500
  37. 37.√92 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  38. 38.√87 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.1 (d) 9.4
  39. 39.Best estimate of 4359 ÷ 82? (a) 5400 (b) 54 (c) 540
  40. 40.Best estimate of 3019 ÷ 72? (a) 4300 (b) 430 (c) 43

Answer key

  1. 85
  2. 34
  3. 5.4
  4. 45
  5. 8.1
  6. 30
  7. 9.4
  8. 82
  9. 48
  10. 64
  11. 13
  12. 5.9
  13. 24
  14. 29
  15. 8.4
  16. 7.2
  17. 75
  18. 7.4
  19. 92
  20. 4.7
  21. 8.6
  22. 67
  23. 22
  24. 15
  25. 8.9
  26. 79
  27. 52
  28. 21
  29. 5.2
  30. 100
  31. 4.8
  32. 13
  33. 57
  34. 92
  35. 23
  36. 15
  37. 9.6
  38. 9.3
  39. 54
  40. 43

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