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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 983 · 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 2129 ÷ 41? (a) 530 (b) 53 (c) 5300
  2. 2.√77 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 9.1
  3. 3.Best estimate of 1309 ÷ 32? (a) 440 (b) 44 (c) 4400
  4. 4.√74 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.5 (d) 8.6
  5. 5.√87 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.2 (d) 9.3
  6. 6.√43 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 6.6
  7. 7.√85 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.0
  8. 8.Best estimate of 6777 ÷ 72? (a) 970 (b) 9700 (c) 97
  9. 9.Best estimate of 844 ÷ 21? (a) 4200 (b) 420 (c) 42
  10. 10.Best estimate of 1567 ÷ 56? (a) 2600 (b) 26 (c) 260
  11. 11.√23 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.0 (d) 4.8
  12. 12.Best estimate of 4139 ÷ 48? (a) 8300 (b) 830 (c) 83
  13. 13.√62 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.8 (d) 7.9
  14. 14.Best estimate of 4157 ÷ 82? (a) 5200 (b) 520 (c) 52
  15. 15.Best estimate of 7886 ÷ 87? (a) 8800 (b) 88 (c) 880
  16. 16.Best estimate of 966 ÷ 28? (a) 320 (b) 3200 (c) 32
  17. 17.√29 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.5 (d) 5.4
  18. 18.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 9.8 (d) 10.0
  19. 19.Best estimate of 3788 ÷ 46? (a) 76 (b) 7600 (c) 760
  20. 20.Best estimate of 1424 ÷ 23? (a) 710 (b) 71 (c) 7100
  21. 21.Best estimate of 1221 ÷ 37? (a) 310 (b) 3100 (c) 31
  22. 22.√56 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.6 (d) 7.5
  23. 23.Best estimate of 2832 ÷ 54? (a) 5700 (b) 570 (c) 57
  24. 24.Best estimate of 3144 ÷ 43? (a) 790 (b) 7900 (c) 79
  25. 25.Best estimate of 2214 ÷ 72? (a) 32 (b) 320 (c) 3200
  26. 26.Best estimate of 3080 ÷ 56? (a) 510 (b) 51 (c) 5100
  27. 27.Best estimate of 2009 ÷ 26? (a) 6700 (b) 670 (c) 67
  28. 28.Best estimate of 3687 ÷ 72? (a) 5300 (b) 530 (c) 53
  29. 29.Best estimate of 1143 ÷ 52? (a) 2300 (b) 230 (c) 23
  30. 30.Best estimate of 2702 ÷ 49? (a) 5400 (b) 540 (c) 54
  31. 31.Best estimate of 1095 ÷ 32? (a) 3700 (b) 370 (c) 37
  32. 32.Best estimate of 1407 ÷ 53? (a) 280 (b) 28 (c) 2800
  33. 33.√40 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.4 (d) 6.6
  34. 34.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.7
  35. 35.Best estimate of 5082 ÷ 87? (a) 560 (b) 5600 (c) 56
  36. 36.Best estimate of 3988 ÷ 78? (a) 5000 (b) 500 (c) 50
  37. 37.Best estimate of 4821 ÷ 56? (a) 8000 (b) 800 (c) 80
  38. 38.Best estimate of 1333 ÷ 72? (a) 19 (b) 1900 (c) 190
  39. 39.Best estimate of 5436 ÷ 72? (a) 78 (b) 7800 (c) 780
  40. 40.Best estimate of 3952 ÷ 42? (a) 9900 (b) 99 (c) 990

Answer key

  1. 53
  2. 8.8
  3. 44
  4. 8.6
  5. 9.3
  6. 6.6
  7. 9.2
  8. 97
  9. 42
  10. 26
  11. 4.8
  12. 83
  13. 7.9
  14. 52
  15. 88
  16. 32
  17. 5.4
  18. 9.9
  19. 76
  20. 71
  21. 31
  22. 7.5
  23. 57
  24. 79
  25. 32
  26. 51
  27. 67
  28. 53
  29. 23
  30. 54
  31. 37
  32. 28
  33. 6.3
  34. 9.6
  35. 56
  36. 50
  37. 80
  38. 19
  39. 78
  40. 99

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