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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 934 · 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 1401 ÷ 21? (a) 700 (b) 7000 (c) 70
  2. 2.Best estimate of 755 ÷ 23? (a) 380 (b) 38 (c) 3800
  3. 3.Best estimate of 1395 ÷ 33? (a) 4700 (b) 470 (c) 47
  4. 4.Best estimate of 4124 ÷ 84? (a) 5200 (b) 520 (c) 52
  5. 5.√40 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.3 (d) 6.0
  6. 6.Best estimate of 360 ÷ 27? (a) 12 (b) 1200 (c) 120
  7. 7.Best estimate of 1173 ÷ 58? (a) 200 (b) 2000 (c) 20
  8. 8.Best estimate of 3103 ÷ 58? (a) 5200 (b) 52 (c) 520
  9. 9.√59 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.6 (d) 7.9
  10. 10.√50 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 7.1 (d) 6.8
  11. 11.√74 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.3 (d) 8.4
  12. 12.√34 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 5.6 (d) 5.5
  13. 13.Best estimate of 6115 ÷ 72? (a) 87 (b) 870 (c) 8700
  14. 14.Best estimate of 1883 ÷ 47? (a) 38 (b) 3800 (c) 380
  15. 15.√65 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.1 (d) 8.3
  16. 16.Best estimate of 547 ÷ 26? (a) 1800 (b) 180 (c) 18
  17. 17.Best estimate of 2458 ÷ 28? (a) 82 (b) 8200 (c) 820
  18. 18.Best estimate of 3679 ÷ 72? (a) 530 (b) 5300 (c) 53
  19. 19.√56 to 1 decimal place? (a) 7.7 (b) 7.4 (c) 7.5 (d) 7.6
  20. 20.Best estimate of 4413 ÷ 84? (a) 550 (b) 55 (c) 5500
  21. 21.Best estimate of 4026 ÷ 69? (a) 58 (b) 5800 (c) 580
  22. 22.Best estimate of 641 ÷ 42? (a) 160 (b) 1600 (c) 16
  23. 23.√58 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 7.6 (d) 7.7
  24. 24.Best estimate of 4514 ÷ 48? (a) 900 (b) 90 (c) 9000
  25. 25.Best estimate of 3867 ÷ 81? (a) 480 (b) 48 (c) 4800
  26. 26.Best estimate of 2607 ÷ 32? (a) 87 (b) 870 (c) 8700
  27. 27.Best estimate of 508 ÷ 32? (a) 17 (b) 1700 (c) 170
  28. 28.Best estimate of 3756 ÷ 61? (a) 6300 (b) 63 (c) 630
  29. 29.√82 to 1 decimal place? (a) 9.4 (b) 9.1 (c) 9.3 (d) 9.2
  30. 30.Best estimate of 2461 ÷ 82? (a) 31 (b) 310 (c) 3100
  31. 31.√78 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 8.6
  32. 32.Best estimate of 2866 ÷ 34? (a) 960 (b) 96 (c) 9600
  33. 33.√47 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.0 (d) 6.7
  34. 34.√67 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.1 (d) 8.2
  35. 35.√69 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.0
  36. 36.Best estimate of 1545 ÷ 89? (a) 170 (b) 1700 (c) 17
  37. 37.Best estimate of 2044 ÷ 62? (a) 34 (b) 3400 (c) 340
  38. 38.√21 to 1 decimal place? (a) 4.8 (b) 4.5 (c) 4.6 (d) 4.7
  39. 39.Best estimate of 5687 ÷ 79? (a) 710 (b) 7100 (c) 71
  40. 40.Best estimate of 4372 ÷ 46? (a) 87 (b) 8700 (c) 870

Answer key

  1. 70
  2. 38
  3. 47
  4. 52
  5. 6.3
  6. 12
  7. 20
  8. 52
  9. 7.7
  10. 7.1
  11. 8.6
  12. 5.8
  13. 87
  14. 38
  15. 8.1
  16. 18
  17. 82
  18. 53
  19. 7.5
  20. 55
  21. 58
  22. 16
  23. 7.6
  24. 90
  25. 48
  26. 87
  27. 17
  28. 63
  29. 9.1
  30. 31
  31. 8.8
  32. 96
  33. 6.9
  34. 8.2
  35. 8.3
  36. 17
  37. 34
  38. 4.6
  39. 71
  40. 87

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