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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 233 · 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 1978 ÷ 66? (a) 280 (b) 2800 (c) 28
  2. 2.√31 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.7 (d) 5.4
  3. 3.Best estimate of 1580 ÷ 32? (a) 53 (b) 530 (c) 5300
  4. 4.√20 to 1 decimal place? (a) 4.7 (b) 4.4 (c) 4.5 (d) 4.6
  5. 5.Best estimate of 1582 ÷ 57? (a) 26 (b) 260 (c) 2600
  6. 6.√76 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.7 (d) 8.6
  7. 7.Best estimate of 430 ÷ 34? (a) 1400 (b) 14 (c) 140
  8. 8.√29 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.3 (d) 5.2
  9. 9.√37 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.2 (d) 6.0
  10. 10.Best estimate of 608 ÷ 26? (a) 200 (b) 2000 (c) 20
  11. 11.√92 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.5 (d) 9.6
  12. 12.√35 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 5.9 (d) 6.2
  13. 13.√51 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 7.0 (d) 7.2
  14. 14.Best estimate of 1290 ÷ 72? (a) 180 (b) 18 (c) 1800
  15. 15.Best estimate of 3845 ÷ 42? (a) 96 (b) 960 (c) 9600
  16. 16.Best estimate of 3581 ÷ 72? (a) 5100 (b) 510 (c) 51
  17. 17.√75 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 8.6 (d) 8.7
  18. 18.Best estimate of 1555 ÷ 62? (a) 2600 (b) 260 (c) 26
  19. 19.√30 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.7 (d) 5.4
  20. 20.Best estimate of 894 ÷ 21? (a) 4500 (b) 450 (c) 45
  21. 21.Best estimate of 2551 ÷ 49? (a) 51 (b) 5100 (c) 510
  22. 22.Best estimate of 2675 ÷ 62? (a) 4500 (b) 450 (c) 45
  23. 23.√79 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 8.9 (d) 9.1
  24. 24.Best estimate of 1706 ÷ 26? (a) 5700 (b) 570 (c) 57
  25. 25.Best estimate of 2658 ÷ 54? (a) 53 (b) 530 (c) 5300
  26. 26.Best estimate of 1387 ÷ 49? (a) 280 (b) 28 (c) 2800
  27. 27.Best estimate of 7285 ÷ 87? (a) 81 (b) 8100 (c) 810
  28. 28.Best estimate of 1815 ÷ 37? (a) 45 (b) 450 (c) 4500
  29. 29.√34 to 1 decimal place? (a) 5.8 (b) 5.6 (c) 5.5 (d) 5.7
  30. 30.Best estimate of 4651 ÷ 82? (a) 58 (b) 580 (c) 5800
  31. 31.√77 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 8.6
  32. 32.Best estimate of 2153 ÷ 24? (a) 1080 (b) 10800 (c) 108
  33. 33.√21 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.8 (d) 4.7
  34. 34.Best estimate of 2726 ÷ 63? (a) 4500 (b) 45 (c) 450
  35. 35.√69 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.0
  36. 36.Best estimate of 4314 ÷ 88? (a) 48 (b) 480 (c) 4800
  37. 37.Best estimate of 3787 ÷ 83? (a) 470 (b) 47 (c) 4700
  38. 38.√24 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.9 (d) 4.7
  39. 39.√50 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 7.3 (d) 7.2
  40. 40.Best estimate of 2812 ÷ 34? (a) 94 (b) 9400 (c) 940

Answer key

  1. 28
  2. 5.6
  3. 53
  4. 4.5
  5. 26
  6. 8.7
  7. 14
  8. 5.4
  9. 6.1
  10. 20
  11. 9.6
  12. 5.9
  13. 7.1
  14. 18
  15. 96
  16. 51
  17. 8.7
  18. 26
  19. 5.5
  20. 45
  21. 51
  22. 45
  23. 8.9
  24. 57
  25. 53
  26. 28
  27. 81
  28. 45
  29. 5.8
  30. 58
  31. 8.8
  32. 108
  33. 4.6
  34. 45
  35. 8.3
  36. 48
  37. 47
  38. 4.9
  39. 7.1
  40. 94

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