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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 177 · 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 2524 ÷ 38? (a) 6300 (b) 63 (c) 630
  2. 2.√82 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.1 (d) 9.2
  3. 3.Best estimate of 5762 ÷ 76? (a) 7200 (b) 72 (c) 720
  4. 4.√48 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.9 (d) 6.8
  5. 5.√56 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.4 (d) 7.5
  6. 6.Best estimate of 1419 ÷ 86? (a) 16 (b) 1600 (c) 160
  7. 7.Best estimate of 1402 ÷ 21? (a) 7000 (b) 700 (c) 70
  8. 8.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.8
  9. 9.√88 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.1
  10. 10.√34 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.6 (d) 5.8
  11. 11.Best estimate of 1784 ÷ 36? (a) 450 (b) 4500 (c) 45
  12. 12.√62 to 1 decimal place? (a) 8.0 (b) 7.7 (c) 7.8 (d) 7.9
  13. 13.Best estimate of 2128 ÷ 37? (a) 5300 (b) 53 (c) 530
  14. 14.Best estimate of 4915 ÷ 62? (a) 82 (b) 8200 (c) 820
  15. 15.√31 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.7 (d) 5.4
  16. 16.Best estimate of 2555 ÷ 71? (a) 3700 (b) 37 (c) 370
  17. 17.Best estimate of 1976 ÷ 52? (a) 40 (b) 400 (c) 4000
  18. 18.√80 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.9
  19. 19.Best estimate of 1337 ÷ 88? (a) 150 (b) 1500 (c) 15
  20. 20.Best estimate of 3518 ÷ 77? (a) 44 (b) 4400 (c) 440
  21. 21.Best estimate of 4246 ÷ 86? (a) 47 (b) 470 (c) 4700
  22. 22.Best estimate of 1384 ÷ 22? (a) 6900 (b) 690 (c) 69
  23. 23.√40 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.3 (d) 6.0
  24. 24.Best estimate of 1534 ÷ 23? (a) 7700 (b) 77 (c) 770
  25. 25.√96 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 10.1
  26. 26.√74 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.3 (d) 8.5
  27. 27.√65 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.4
  28. 28.√79 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.8 (d) 8.9
  29. 29.Best estimate of 792 ÷ 66? (a) 1100 (b) 11 (c) 110
  30. 30.√30 to 1 decimal place? (a) 5.3 (b) 5.4 (c) 5.5 (d) 5.2
  31. 31.Best estimate of 4019 ÷ 49? (a) 8000 (b) 800 (c) 80
  32. 32.√46 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 6.8 (d) 6.9
  33. 33.Best estimate of 316 ÷ 24? (a) 16 (b) 1600 (c) 160
  34. 34.Best estimate of 2764 ÷ 89? (a) 3100 (b) 310 (c) 31
  35. 35.Best estimate of 4738 ÷ 86? (a) 530 (b) 5300 (c) 53
  36. 36.√23 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 5.0 (d) 5.1
  37. 37.Best estimate of 3766 ÷ 42? (a) 940 (b) 94 (c) 9400
  38. 38.Best estimate of 3844 ÷ 64? (a) 6400 (b) 64 (c) 640
  39. 39.Best estimate of 577 ÷ 32? (a) 190 (b) 1900 (c) 19
  40. 40.Best estimate of 595 ÷ 29? (a) 2000 (b) 200 (c) 20

Answer key

  1. 63
  2. 9.1
  3. 72
  4. 6.9
  5. 7.5
  6. 16
  7. 70
  8. 9.6
  9. 9.4
  10. 5.8
  11. 45
  12. 7.9
  13. 53
  14. 82
  15. 5.6
  16. 37
  17. 40
  18. 8.9
  19. 15
  20. 44
  21. 47
  22. 69
  23. 6.3
  24. 77
  25. 9.8
  26. 8.6
  27. 8.1
  28. 8.9
  29. 11
  30. 5.5
  31. 80
  32. 6.8
  33. 16
  34. 31
  35. 53
  36. 4.8
  37. 94
  38. 64
  39. 19
  40. 20

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