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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 301 · 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.√55 to 1 decimal place? (a) 7.5 (b) 7.7 (c) 7.4 (d) 7.6
  2. 2.Best estimate of 4867 ÷ 53? (a) 9700 (b) 970 (c) 97
  3. 3.√22 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.7 (d) 4.6
  4. 4.Best estimate of 1932 ÷ 36? (a) 480 (b) 4800 (c) 48
  5. 5.√34 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 6.1 (d) 5.9
  6. 6.Best estimate of 5157 ÷ 66? (a) 740 (b) 7400 (c) 74
  7. 7.Best estimate of 909 ÷ 57? (a) 1500 (b) 15 (c) 150
  8. 8.Best estimate of 2282 ÷ 88? (a) 25 (b) 2500 (c) 250
  9. 9.√67 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 7.9 (d) 8.1
  10. 10.Best estimate of 2827 ÷ 53? (a) 570 (b) 57 (c) 5700
  11. 11.Best estimate of 1380 ÷ 31? (a) 460 (b) 4600 (c) 46
  12. 12.Best estimate of 1938 ÷ 37? (a) 4800 (b) 48 (c) 480
  13. 13.Best estimate of 5668 ÷ 82? (a) 71 (b) 710 (c) 7100
  14. 14.Best estimate of 1808 ÷ 28? (a) 600 (b) 6000 (c) 60
  15. 15.Best estimate of 1269 ÷ 52? (a) 2500 (b) 25 (c) 250
  16. 16.√87 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.5 (d) 9.3
  17. 17.√51 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 7.2 (d) 7.1
  18. 18.Best estimate of 3641 ÷ 52? (a) 730 (b) 7300 (c) 73
  19. 19.Best estimate of 1638 ÷ 44? (a) 41 (b) 4100 (c) 410
  20. 20.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.7 (d) 9.6
  21. 21.Best estimate of 5513 ÷ 69? (a) 790 (b) 7900 (c) 79
  22. 22.√30 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  23. 23.√77 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 8.7 (d) 8.8
  24. 24.Best estimate of 1710 ÷ 32? (a) 5700 (b) 57 (c) 570
  25. 25.√44 to 1 decimal place? (a) 6.5 (b) 6.8 (c) 6.6 (d) 6.7
  26. 26.Best estimate of 5561 ÷ 81? (a) 7000 (b) 70 (c) 700
  27. 27.Best estimate of 940 ÷ 57? (a) 160 (b) 1600 (c) 16
  28. 28.Best estimate of 1364 ÷ 86? (a) 150 (b) 1500 (c) 15
  29. 29.Best estimate of 4387 ÷ 73? (a) 6300 (b) 630 (c) 63
  30. 30.√89 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.4 (d) 9.2
  31. 31.Best estimate of 615 ÷ 42? (a) 150 (b) 15 (c) 1500
  32. 32.Best estimate of 1777 ÷ 43? (a) 44 (b) 4400 (c) 440
  33. 33.Best estimate of 1365 ÷ 71? (a) 2000 (b) 20 (c) 200
  34. 34.Best estimate of 5136 ÷ 72? (a) 73 (b) 7300 (c) 730
  35. 35.Best estimate of 421 ÷ 32? (a) 140 (b) 1400 (c) 14
  36. 36.Best estimate of 813 ÷ 58? (a) 14 (b) 1400 (c) 140
  37. 37.√31 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.7 (d) 5.5
  38. 38.Best estimate of 2089 ÷ 52? (a) 42 (b) 420 (c) 4200
  39. 39.Best estimate of 4720 ÷ 81? (a) 590 (b) 59 (c) 5900
  40. 40.√37 to 1 decimal place? (a) 6.0 (b) 5.8 (c) 5.9 (d) 6.1

Answer key

  1. 7.4
  2. 97
  3. 4.7
  4. 48
  5. 5.8
  6. 74
  7. 15
  8. 25
  9. 8.2
  10. 57
  11. 46
  12. 48
  13. 71
  14. 60
  15. 25
  16. 9.3
  17. 7.1
  18. 73
  19. 41
  20. 9.9
  21. 79
  22. 5.5
  23. 8.8
  24. 57
  25. 6.6
  26. 70
  27. 16
  28. 15
  29. 63
  30. 9.4
  31. 15
  32. 44
  33. 20
  34. 73
  35. 14
  36. 14
  37. 5.6
  38. 42
  39. 59
  40. 6.1

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