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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 96 · 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.√67 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 8.2 (d) 8.0
  2. 2.√66 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 7.8 (d) 8.0
  3. 3.Best estimate of 636 ÷ 36? (a) 16 (b) 1600 (c) 160
  4. 4.Best estimate of 481 ÷ 34? (a) 1600 (b) 160 (c) 16
  5. 5.√58 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  6. 6.√76 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 8.6
  7. 7.√51 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.0 (d) 7.1
  8. 8.√86 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.3 (d) 9.4
  9. 9.Best estimate of 2524 ÷ 27? (a) 840 (b) 8400 (c) 84
  10. 10.Best estimate of 7378 ÷ 86? (a) 8200 (b) 820 (c) 82
  11. 11.Best estimate of 5671 ÷ 88? (a) 63 (b) 630 (c) 6300
  12. 12.√48 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.9 (d) 7.0
  13. 13.Best estimate of 934 ÷ 72? (a) 13 (b) 1300 (c) 130
  14. 14.Best estimate of 1480 ÷ 87? (a) 160 (b) 16 (c) 1600
  15. 15.Best estimate of 1329 ÷ 36? (a) 33 (b) 330 (c) 3300
  16. 16.Best estimate of 361 ÷ 27? (a) 120 (b) 1200 (c) 12
  17. 17.Best estimate of 3636 ÷ 47? (a) 73 (b) 730 (c) 7300
  18. 18.Best estimate of 1018 ÷ 42? (a) 2500 (b) 250 (c) 25
  19. 19.√30 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.4 (d) 5.3
  20. 20.√40 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.5 (d) 6.4
  21. 21.Best estimate of 1374 ÷ 54? (a) 270 (b) 2700 (c) 27
  22. 22.√69 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.1
  23. 23.Best estimate of 3498 ÷ 39? (a) 870 (b) 8700 (c) 87
  24. 24.Best estimate of 2641 ÷ 52? (a) 53 (b) 530 (c) 5300
  25. 25.√78 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 8.7
  26. 26.√65 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.4
  27. 27.Best estimate of 954 ÷ 67? (a) 140 (b) 14 (c) 1400
  28. 28.Best estimate of 2545 ÷ 36? (a) 640 (b) 6400 (c) 64
  29. 29.Best estimate of 3623 ÷ 88? (a) 400 (b) 4000 (c) 40
  30. 30.Best estimate of 2709 ÷ 32? (a) 90 (b) 9000 (c) 900
  31. 31.√63 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  32. 32.√47 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.0 (d) 6.7
  33. 33.Best estimate of 1231 ÷ 84? (a) 1500 (b) 150 (c) 15
  34. 34.√94 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.6 (d) 9.7
  35. 35.√96 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 10.0 (d) 9.8
  36. 36.Best estimate of 1668 ÷ 66? (a) 2400 (b) 24 (c) 240
  37. 37.√23 to 1 decimal place? (a) 4.6 (b) 4.9 (c) 4.7 (d) 4.8
  38. 38.Best estimate of 867 ÷ 27? (a) 2900 (b) 29 (c) 290
  39. 39.√70 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.4 (d) 8.3
  40. 40.√59 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.6 (d) 7.8

Answer key

  1. 8.2
  2. 8.1
  3. 16
  4. 16
  5. 7.6
  6. 8.7
  7. 7.1
  8. 9.3
  9. 84
  10. 82
  11. 63
  12. 6.9
  13. 13
  14. 16
  15. 33
  16. 12
  17. 73
  18. 25
  19. 5.5
  20. 6.3
  21. 27
  22. 8.3
  23. 87
  24. 53
  25. 8.8
  26. 8.1
  27. 14
  28. 64
  29. 40
  30. 90
  31. 7.9
  32. 6.9
  33. 15
  34. 9.7
  35. 9.8
  36. 24
  37. 4.8
  38. 29
  39. 8.4
  40. 7.7

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