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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 686 · 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.√74 to 1 decimal place? (a) 8.8 (b) 8.5 (c) 8.6 (d) 8.7
  2. 2.Best estimate of 1491 ÷ 84? (a) 190 (b) 1900 (c) 19
  3. 3.Best estimate of 2082 ÷ 64? (a) 35 (b) 350 (c) 3500
  4. 4.√30 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.3
  5. 5.Best estimate of 2432 ÷ 83? (a) 3000 (b) 30 (c) 300
  6. 6.Best estimate of 778 ÷ 34? (a) 26 (b) 2600 (c) 260
  7. 7.Best estimate of 4773 ÷ 88? (a) 5300 (b) 530 (c) 53
  8. 8.√98 to 1 decimal place? (a) 10.2 (b) 10.1 (c) 10.0 (d) 9.9
  9. 9.√96 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.7 (d) 9.9
  10. 10.Best estimate of 2585 ÷ 32? (a) 86 (b) 860 (c) 8600
  11. 11.Best estimate of 1216 ÷ 58? (a) 2000 (b) 20 (c) 200
  12. 12.Best estimate of 598 ÷ 24? (a) 3000 (b) 300 (c) 30
  13. 13.Best estimate of 2280 ÷ 36? (a) 570 (b) 5700 (c) 57
  14. 14.Best estimate of 1335 ÷ 63? (a) 2200 (b) 220 (c) 22
  15. 15.√53 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.4
  16. 16.Best estimate of 392 ÷ 32? (a) 1300 (b) 13 (c) 130
  17. 17.√44 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.7 (d) 6.4
  18. 18.√89 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.1 (d) 9.2
  19. 19.Best estimate of 4640 ÷ 77? (a) 58 (b) 5800 (c) 580
  20. 20.Best estimate of 2618 ÷ 31? (a) 8700 (b) 870 (c) 87
  21. 21.√45 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.6 (d) 6.8
  22. 22.√71 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.1
  23. 23.Best estimate of 373 ÷ 24? (a) 1900 (b) 190 (c) 19
  24. 24.Best estimate of 1613 ÷ 46? (a) 320 (b) 32 (c) 3200
  25. 25.√59 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.4 (d) 7.5
  26. 26.Best estimate of 1128 ÷ 74? (a) 1600 (b) 160 (c) 16
  27. 27.Best estimate of 1400 ÷ 52? (a) 2800 (b) 280 (c) 28
  28. 28.Best estimate of 2212 ÷ 27? (a) 740 (b) 7400 (c) 74
  29. 29.Best estimate of 2178 ÷ 71? (a) 310 (b) 3100 (c) 31
  30. 30.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.0 (d) 5.3
  31. 31.Best estimate of 1228 ÷ 77? (a) 150 (b) 15 (c) 1500
  32. 32.√50 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.2 (d) 6.9
  33. 33.Best estimate of 5418 ÷ 82? (a) 680 (b) 68 (c) 6800
  34. 34.Best estimate of 3081 ÷ 33? (a) 1030 (b) 103 (c) 10300
  35. 35.√20 to 1 decimal place? (a) 4.2 (b) 4.3 (c) 4.4 (d) 4.5
  36. 36.√67 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 8.2
  37. 37.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.2
  38. 38.√34 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 5.8
  39. 39.Best estimate of 4640 ÷ 81? (a) 580 (b) 5800 (c) 58
  40. 40.Best estimate of 2791 ÷ 76? (a) 3500 (b) 350 (c) 35

Answer key

  1. 8.6
  2. 19
  3. 35
  4. 5.5
  5. 30
  6. 26
  7. 53
  8. 9.9
  9. 9.8
  10. 86
  11. 20
  12. 30
  13. 57
  14. 22
  15. 7.3
  16. 13
  17. 6.6
  18. 9.4
  19. 58
  20. 87
  21. 6.7
  22. 8.4
  23. 19
  24. 32
  25. 7.7
  26. 16
  27. 28
  28. 74
  29. 31
  30. 5.1
  31. 15
  32. 7.1
  33. 68
  34. 103
  35. 4.5
  36. 8.2
  37. 6.3
  38. 5.8
  39. 58
  40. 35

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