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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 632 · 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.√32 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.4 (d) 5.5
  2. 2.√98 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 9.9 (d) 9.8
  3. 3.Best estimate of 1135 ÷ 48? (a) 2300 (b) 230 (c) 23
  4. 4.√40 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.6 (d) 6.4
  5. 5.√65 to 1 decimal place? (a) 8.1 (b) 7.8 (c) 8.0 (d) 7.9
  6. 6.Best estimate of 881 ÷ 29? (a) 2900 (b) 29 (c) 290
  7. 7.√31 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.5 (d) 5.3
  8. 8.√44 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.7 (d) 6.6
  9. 9.√20 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.7 (d) 4.8
  10. 10.Best estimate of 1918 ÷ 46? (a) 380 (b) 38 (c) 3800
  11. 11.√58 to 1 decimal place? (a) 7.3 (b) 7.6 (c) 7.5 (d) 7.4
  12. 12.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 6.9 (d) 7.0
  13. 13.Best estimate of 656 ÷ 32? (a) 22 (b) 2200 (c) 220
  14. 14.√74 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.7 (d) 8.6
  15. 15.√24 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 4.7 (d) 4.6
  16. 16.√45 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.6 (d) 6.8
  17. 17.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.0 (d) 9.7
  18. 18.√87 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.3 (d) 9.1
  19. 19.√35 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.2 (d) 6.1
  20. 20.√48 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.7 (d) 6.8
  21. 21.Best estimate of 4370 ÷ 62? (a) 730 (b) 7300 (c) 73
  22. 22.Best estimate of 1967 ÷ 46? (a) 39 (b) 390 (c) 3900
  23. 23.Best estimate of 5415 ÷ 88? (a) 6000 (b) 60 (c) 600
  24. 24.Best estimate of 2974 ÷ 77? (a) 3700 (b) 37 (c) 370
  25. 25.Best estimate of 1162 ÷ 76? (a) 150 (b) 1500 (c) 15
  26. 26.√26 to 1 decimal place? (a) 5.1 (b) 4.8 (c) 5.0 (d) 4.9
  27. 27.Best estimate of 2097 ÷ 83? (a) 260 (b) 26 (c) 2600
  28. 28.√85 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 8.9
  29. 29.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.3 (d) 7.5
  30. 30.Best estimate of 1617 ÷ 56? (a) 270 (b) 2700 (c) 27
  31. 31.Best estimate of 3749 ÷ 78? (a) 4700 (b) 47 (c) 470
  32. 32.√62 to 1 decimal place? (a) 8.2 (b) 8.0 (c) 7.9 (d) 8.1
  33. 33.√51 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.4 (d) 7.3
  34. 34.Best estimate of 2765 ÷ 58? (a) 46 (b) 4600 (c) 460
  35. 35.√77 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.8 (d) 8.9
  36. 36.Best estimate of 737 ÷ 21? (a) 3700 (b) 37 (c) 370
  37. 37.√72 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.8
  38. 38.√92 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.5
  39. 39.√94 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.8 (d) 9.6
  40. 40.√30 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.6 (d) 5.5

Answer key

  1. 5.7
  2. 9.9
  3. 23
  4. 6.3
  5. 8.1
  6. 29
  7. 5.6
  8. 6.6
  9. 4.5
  10. 38
  11. 7.6
  12. 7.1
  13. 22
  14. 8.6
  15. 4.9
  16. 6.7
  17. 9.8
  18. 9.3
  19. 5.9
  20. 6.9
  21. 73
  22. 39
  23. 60
  24. 37
  25. 15
  26. 5.1
  27. 26
  28. 9.2
  29. 7.4
  30. 27
  31. 47
  32. 7.9
  33. 7.1
  34. 46
  35. 8.8
  36. 37
  37. 8.5
  38. 9.6
  39. 9.7
  40. 5.5

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