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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 34 · 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 2985 ÷ 46? (a) 600 (b) 6000 (c) 60
  2. 2.√35 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 5.9 (d) 6.0
  3. 3.Best estimate of 255 ÷ 21? (a) 130 (b) 1300 (c) 13
  4. 4.Best estimate of 4200 ÷ 72? (a) 6000 (b) 60 (c) 600
  5. 5.Best estimate of 323 ÷ 22? (a) 1600 (b) 16 (c) 160
  6. 6.Best estimate of 4493 ÷ 54? (a) 9000 (b) 900 (c) 90
  7. 7.Best estimate of 3720 ÷ 56? (a) 62 (b) 6200 (c) 620
  8. 8.√67 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.5 (d) 8.3
  9. 9.Best estimate of 4918 ÷ 67? (a) 70 (b) 700 (c) 7000
  10. 10.Best estimate of 4341 ÷ 48? (a) 870 (b) 8700 (c) 87
  11. 11.Best estimate of 2582 ÷ 56? (a) 43 (b) 4300 (c) 430
  12. 12.√77 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 8.8
  13. 13.Best estimate of 3474 ÷ 46? (a) 690 (b) 6900 (c) 69
  14. 14.Best estimate of 1318 ÷ 24? (a) 6600 (b) 660 (c) 66
  15. 15.√58 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.3
  16. 16.Best estimate of 605 ÷ 33? (a) 200 (b) 20 (c) 2000
  17. 17.Best estimate of 3031 ÷ 49? (a) 610 (b) 6100 (c) 61
  18. 18.Best estimate of 2049 ÷ 83? (a) 26 (b) 260 (c) 2600
  19. 19.Best estimate of 2436 ÷ 29? (a) 8100 (b) 810 (c) 81
  20. 20.√53 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.3 (d) 7.5
  21. 21.√41 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.3 (d) 6.1
  22. 22.Best estimate of 1027 ÷ 32? (a) 34 (b) 340 (c) 3400
  23. 23.Best estimate of 3603 ÷ 39? (a) 9000 (b) 900 (c) 90
  24. 24.Best estimate of 4203 ÷ 56? (a) 7000 (b) 70 (c) 700
  25. 25.Best estimate of 1082 ÷ 22? (a) 540 (b) 5400 (c) 54
  26. 26.Best estimate of 4466 ÷ 82? (a) 560 (b) 56 (c) 5600
  27. 27.Best estimate of 1932 ÷ 21? (a) 970 (b) 97 (c) 9700
  28. 28.Best estimate of 1165 ÷ 43? (a) 2900 (b) 290 (c) 29
  29. 29.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.5 (d) 9.6
  30. 30.√22 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.6 (d) 4.8
  31. 31.Best estimate of 714 ÷ 36? (a) 1800 (b) 18 (c) 180
  32. 32.√38 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.2 (d) 6.4
  33. 33.√28 to 1 decimal place? (a) 5.5 (b) 5.2 (c) 5.3 (d) 5.4
  34. 34.Best estimate of 400 ÷ 26? (a) 13 (b) 1300 (c) 130
  35. 35.Best estimate of 1670 ÷ 63? (a) 28 (b) 280 (c) 2800
  36. 36.√65 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.0
  37. 37.Best estimate of 4542 ÷ 62? (a) 760 (b) 7600 (c) 76
  38. 38.√46 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.0 (d) 6.7
  39. 39.Best estimate of 7562 ÷ 83? (a) 9500 (b) 95 (c) 950
  40. 40.√74 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.6

Answer key

  1. 60
  2. 5.9
  3. 13
  4. 60
  5. 16
  6. 90
  7. 62
  8. 8.2
  9. 70
  10. 87
  11. 43
  12. 8.8
  13. 69
  14. 66
  15. 7.6
  16. 20
  17. 61
  18. 26
  19. 81
  20. 7.3
  21. 6.4
  22. 34
  23. 90
  24. 70
  25. 54
  26. 56
  27. 97
  28. 29
  29. 9.7
  30. 4.7
  31. 18
  32. 6.2
  33. 5.3
  34. 13
  35. 28
  36. 8.1
  37. 76
  38. 6.8
  39. 95
  40. 8.6

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