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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 13 · 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 718 ÷ 33? (a) 24 (b) 240 (c) 2400
  2. 2.√86 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.6
  3. 3.√96 to 1 decimal place? (a) 10.1 (b) 9.8 (c) 10.0 (d) 9.9
  4. 4.Best estimate of 1866 ÷ 22? (a) 930 (b) 93 (c) 9300
  5. 5.√38 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.2
  6. 6.Best estimate of 1788 ÷ 88? (a) 200 (b) 20 (c) 2000
  7. 7.√44 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.4 (d) 6.5
  8. 8.Best estimate of 6644 ÷ 73? (a) 9500 (b) 95 (c) 950
  9. 9.√58 to 1 decimal place? (a) 7.6 (b) 7.9 (c) 7.8 (d) 7.7
  10. 10.√22 to 1 decimal place? (a) 4.6 (b) 4.4 (c) 4.7 (d) 4.5
  11. 11.√41 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.4
  12. 12.√45 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.5 (d) 6.4
  13. 13.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.0 (d) 8.9
  14. 14.√70 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.7 (d) 8.5
  15. 15.Best estimate of 5937 ÷ 63? (a) 990 (b) 9900 (c) 99
  16. 16.Best estimate of 785 ÷ 24? (a) 390 (b) 3900 (c) 39
  17. 17.Best estimate of 5819 ÷ 72? (a) 830 (b) 8300 (c) 83
  18. 18.Best estimate of 869 ÷ 23? (a) 43 (b) 4300 (c) 430
  19. 19.Best estimate of 4725 ÷ 73? (a) 6800 (b) 68 (c) 680
  20. 20.√89 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.4 (d) 9.6
  21. 21.Best estimate of 2848 ÷ 49? (a) 57 (b) 570 (c) 5700
  22. 22.Best estimate of 3322 ÷ 71? (a) 4700 (b) 470 (c) 47
  23. 23.Best estimate of 961 ÷ 56? (a) 160 (b) 16 (c) 1600
  24. 24.√52 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.3 (d) 7.2
  25. 25.√23 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 4.6 (d) 4.5
  26. 26.Best estimate of 5042 ÷ 89? (a) 560 (b) 56 (c) 5600
  27. 27.√42 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.7 (d) 6.4
  28. 28.√31 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.3
  29. 29.Best estimate of 7340 ÷ 79? (a) 920 (b) 9200 (c) 92
  30. 30.Best estimate of 1226 ÷ 84? (a) 150 (b) 1500 (c) 15
  31. 31.√51 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.3 (d) 7.2
  32. 32.Best estimate of 1355 ÷ 26? (a) 450 (b) 45 (c) 4500
  33. 33.Best estimate of 1452 ÷ 56? (a) 24 (b) 240 (c) 2400
  34. 34.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.3 (d) 7.6
  35. 35.√72 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.4
  36. 36.Best estimate of 2921 ÷ 44? (a) 7300 (b) 730 (c) 73
  37. 37.√34 to 1 decimal place? (a) 5.8 (b) 6.1 (c) 5.9 (d) 6.0
  38. 38.Best estimate of 1804 ÷ 21? (a) 900 (b) 9000 (c) 90
  39. 39.Best estimate of 2745 ÷ 72? (a) 3900 (b) 390 (c) 39
  40. 40.Best estimate of 1725 ÷ 26? (a) 580 (b) 58 (c) 5800

Answer key

  1. 24
  2. 9.3
  3. 9.8
  4. 93
  5. 6.2
  6. 20
  7. 6.6
  8. 95
  9. 7.6
  10. 4.7
  11. 6.4
  12. 6.7
  13. 9.1
  14. 8.4
  15. 99
  16. 39
  17. 83
  18. 43
  19. 68
  20. 9.4
  21. 57
  22. 47
  23. 16
  24. 7.2
  25. 4.8
  26. 56
  27. 6.5
  28. 5.6
  29. 92
  30. 15
  31. 7.1
  32. 45
  33. 24
  34. 7.4
  35. 8.5
  36. 73
  37. 5.8
  38. 90
  39. 39
  40. 58

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