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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 989 · 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 3619 ÷ 86? (a) 40 (b) 400 (c) 4000
  2. 2.√74 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.6 (d) 8.4
  3. 3.√88 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.4 (d) 9.7
  4. 4.√48 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 6.9 (d) 6.7
  5. 5.Best estimate of 5406 ÷ 62? (a) 90 (b) 900 (c) 9000
  6. 6.Best estimate of 3359 ÷ 62? (a) 5600 (b) 56 (c) 560
  7. 7.Best estimate of 2124 ÷ 24? (a) 1060 (b) 10600 (c) 106
  8. 8.√21 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.4 (d) 4.6
  9. 9.Best estimate of 1396 ÷ 76? (a) 17 (b) 1700 (c) 170
  10. 10.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.2 (d) 5.1
  11. 11.Best estimate of 3414 ÷ 42? (a) 850 (b) 85 (c) 8500
  12. 12.√87 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.6
  13. 13.Best estimate of 2604 ÷ 29? (a) 8700 (b) 87 (c) 870
  14. 14.Best estimate of 3001 ÷ 53? (a) 60 (b) 600 (c) 6000
  15. 15.√94 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.4
  16. 16.Best estimate of 2060 ÷ 34? (a) 6900 (b) 69 (c) 690
  17. 17.√79 to 1 decimal place? (a) 8.6 (b) 8.9 (c) 8.8 (d) 8.7
  18. 18.Best estimate of 1617 ÷ 73? (a) 2300 (b) 23 (c) 230
  19. 19.Best estimate of 2510 ÷ 56? (a) 420 (b) 42 (c) 4200
  20. 20.Best estimate of 4188 ÷ 62? (a) 700 (b) 7000 (c) 70
  21. 21.Best estimate of 4097 ÷ 59? (a) 680 (b) 6800 (c) 68
  22. 22.Best estimate of 3634 ÷ 48? (a) 730 (b) 7300 (c) 73
  23. 23.√84 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.2
  24. 24.Best estimate of 924 ÷ 48? (a) 180 (b) 18 (c) 1800
  25. 25.Best estimate of 5738 ÷ 82? (a) 72 (b) 7200 (c) 720
  26. 26.Best estimate of 1248 ÷ 26? (a) 420 (b) 4200 (c) 42
  27. 27.√37 to 1 decimal place? (a) 6.4 (b) 6.1 (c) 6.3 (d) 6.2
  28. 28.Best estimate of 2159 ÷ 77? (a) 27 (b) 2700 (c) 270
  29. 29.Best estimate of 1586 ÷ 62? (a) 260 (b) 2600 (c) 26
  30. 30.√96 to 1 decimal place? (a) 9.7 (b) 10.0 (c) 9.8 (d) 9.9
  31. 31.Best estimate of 3801 ÷ 52? (a) 760 (b) 7600 (c) 76
  32. 32.√43 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.5 (d) 6.8
  33. 33.Best estimate of 4378 ÷ 74? (a) 6300 (b) 630 (c) 63
  34. 34.Best estimate of 2959 ÷ 82? (a) 37 (b) 3700 (c) 370
  35. 35.√58 to 1 decimal place? (a) 7.9 (b) 7.6 (c) 7.7 (d) 7.8
  36. 36.Best estimate of 4902 ÷ 69? (a) 7000 (b) 700 (c) 70
  37. 37.√80 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  38. 38.Best estimate of 1868 ÷ 58? (a) 3100 (b) 310 (c) 31
  39. 39.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.6
  40. 40.Best estimate of 4700 ÷ 88? (a) 520 (b) 52 (c) 5200

Answer key

  1. 40
  2. 8.6
  3. 9.4
  4. 6.9
  5. 90
  6. 56
  7. 106
  8. 4.6
  9. 17
  10. 5.1
  11. 85
  12. 9.3
  13. 87
  14. 60
  15. 9.7
  16. 69
  17. 8.9
  18. 23
  19. 42
  20. 70
  21. 68
  22. 73
  23. 9.2
  24. 18
  25. 72
  26. 42
  27. 6.1
  28. 27
  29. 26
  30. 9.8
  31. 76
  32. 6.6
  33. 63
  34. 37
  35. 7.6
  36. 70
  37. 8.9
  38. 31
  39. 6.3
  40. 52

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