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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 132 · 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.√38 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.2 (d) 5.9
  2. 2.√26 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.2 (d) 5.0
  3. 3.Best estimate of 3223 ÷ 42? (a) 81 (b) 810 (c) 8100
  4. 4.√76 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.8 (d) 8.6
  5. 5.Best estimate of 1061 ÷ 88? (a) 120 (b) 1200 (c) 12
  6. 6.√22 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 5.0 (d) 4.9
  7. 7.√78 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.1 (d) 9.0
  8. 8.Best estimate of 1702 ÷ 37? (a) 4300 (b) 43 (c) 430
  9. 9.Best estimate of 4855 ÷ 82? (a) 6100 (b) 610 (c) 61
  10. 10.Best estimate of 469 ÷ 32? (a) 160 (b) 1600 (c) 16
  11. 11.√88 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.3 (d) 9.4
  12. 12.Best estimate of 2581 ÷ 48? (a) 5200 (b) 520 (c) 52
  13. 13.Best estimate of 3030 ÷ 34? (a) 1010 (b) 10100 (c) 101
  14. 14.Best estimate of 4158 ÷ 64? (a) 69 (b) 690 (c) 6900
  15. 15.Best estimate of 1387 ÷ 49? (a) 280 (b) 2800 (c) 28
  16. 16.Best estimate of 4167 ÷ 79? (a) 5200 (b) 520 (c) 52
  17. 17.Best estimate of 3331 ÷ 36? (a) 8300 (b) 83 (c) 830
  18. 18.Best estimate of 4207 ÷ 52? (a) 8400 (b) 840 (c) 84
  19. 19.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.8
  20. 20.Best estimate of 1699 ÷ 46? (a) 340 (b) 3400 (c) 34
  21. 21.Best estimate of 1695 ÷ 37? (a) 42 (b) 4200 (c) 420
  22. 22.Best estimate of 3072 ÷ 71? (a) 44 (b) 4400 (c) 440
  23. 23.Best estimate of 1542 ÷ 46? (a) 310 (b) 31 (c) 3100
  24. 24.Best estimate of 598 ÷ 24? (a) 30 (b) 300 (c) 3000
  25. 25.√61 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.7 (d) 7.5
  26. 26.√45 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.6 (d) 6.5
  27. 27.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.0
  28. 28.Best estimate of 415 ÷ 32? (a) 14 (b) 140 (c) 1400
  29. 29.Best estimate of 2776 ÷ 54? (a) 5600 (b) 56 (c) 560
  30. 30.Best estimate of 1498 ÷ 46? (a) 300 (b) 3000 (c) 30
  31. 31.√74 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.6 (d) 8.5
  32. 32.√96 to 1 decimal place? (a) 9.7 (b) 10.0 (c) 9.9 (d) 9.8
  33. 33.√51 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 7.3
  34. 34.Best estimate of 4374 ÷ 47? (a) 87 (b) 870 (c) 8700
  35. 35.√28 to 1 decimal place? (a) 5.0 (b) 5.3 (c) 5.1 (d) 5.2
  36. 36.Best estimate of 3119 ÷ 64? (a) 5200 (b) 520 (c) 52
  37. 37.√43 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.9
  38. 38.√35 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 6.1 (d) 5.9
  39. 39.Best estimate of 5969 ÷ 81? (a) 75 (b) 750 (c) 7500
  40. 40.√98 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.9

Answer key

  1. 6.2
  2. 5.1
  3. 81
  4. 8.7
  5. 12
  6. 4.7
  7. 8.8
  8. 43
  9. 61
  10. 16
  11. 9.4
  12. 52
  13. 101
  14. 69
  15. 28
  16. 52
  17. 83
  18. 84
  19. 9.6
  20. 34
  21. 42
  22. 44
  23. 31
  24. 30
  25. 7.8
  26. 6.7
  27. 7.1
  28. 14
  29. 56
  30. 30
  31. 8.6
  32. 9.8
  33. 7.1
  34. 87
  35. 5.3
  36. 52
  37. 6.6
  38. 5.9
  39. 75
  40. 9.9

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