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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 186 · 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 1725 ÷ 21? (a) 860 (b) 86 (c) 8600
  2. 2.√76 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.5
  3. 3.Best estimate of 1052 ÷ 34? (a) 3500 (b) 350 (c) 35
  4. 4.Best estimate of 1103 ÷ 64? (a) 18 (b) 1800 (c) 180
  5. 5.√44 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.5 (d) 6.3
  6. 6.√69 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.1 (d) 8.3
  7. 7.√58 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.4
  8. 8.√32 to 1 decimal place? (a) 5.5 (b) 5.7 (c) 5.8 (d) 5.6
  9. 9.√71 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.4 (d) 8.3
  10. 10.Best estimate of 2672 ÷ 71? (a) 3800 (b) 38 (c) 380
  11. 11.Best estimate of 1699 ÷ 37? (a) 42 (b) 4200 (c) 420
  12. 12.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.2 (d) 6.1
  13. 13.Best estimate of 968 ÷ 36? (a) 240 (b) 24 (c) 2400
  14. 14.√94 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  15. 15.Best estimate of 4787 ÷ 77? (a) 6000 (b) 600 (c) 60
  16. 16.Best estimate of 1582 ÷ 86? (a) 180 (b) 1800 (c) 18
  17. 17.Best estimate of 1760 ÷ 21? (a) 880 (b) 8800 (c) 88
  18. 18.√98 to 1 decimal place? (a) 10.1 (b) 9.9 (c) 9.8 (d) 10.0
  19. 19.Best estimate of 890 ÷ 41? (a) 22 (b) 220 (c) 2200
  20. 20.Best estimate of 2563 ÷ 63? (a) 4300 (b) 43 (c) 430
  21. 21.√88 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.4
  22. 22.√51 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  23. 23.Best estimate of 1541 ÷ 21? (a) 7700 (b) 770 (c) 77
  24. 24.√50 to 1 decimal place? (a) 7.2 (b) 7.4 (c) 7.1 (d) 7.3
  25. 25.√52 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.4 (d) 7.2
  26. 26.Best estimate of 3425 ÷ 52? (a) 6900 (b) 69 (c) 690
  27. 27.√83 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.1 (d) 9.3
  28. 28.√90 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.6 (d) 9.5
  29. 29.Best estimate of 1546 ÷ 78? (a) 1900 (b) 190 (c) 19
  30. 30.Best estimate of 2813 ÷ 47? (a) 5600 (b) 560 (c) 56
  31. 31.√38 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.4
  32. 32.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.6 (d) 7.7
  33. 33.Best estimate of 935 ÷ 22? (a) 4700 (b) 47 (c) 470
  34. 34.Best estimate of 1938 ÷ 52? (a) 39 (b) 3900 (c) 390
  35. 35.√75 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.7 (d) 8.4
  36. 36.Best estimate of 1899 ÷ 27? (a) 6300 (b) 63 (c) 630
  37. 37.Best estimate of 6265 ÷ 87? (a) 70 (b) 700 (c) 7000
  38. 38.√24 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.8 (d) 4.9
  39. 39.Best estimate of 1681 ÷ 44? (a) 4200 (b) 42 (c) 420
  40. 40.Best estimate of 1237 ÷ 27? (a) 41 (b) 410 (c) 4100

Answer key

  1. 86
  2. 8.7
  3. 35
  4. 18
  5. 6.6
  6. 8.3
  7. 7.6
  8. 5.7
  9. 8.4
  10. 38
  11. 42
  12. 6.3
  13. 24
  14. 9.7
  15. 60
  16. 18
  17. 88
  18. 9.9
  19. 22
  20. 43
  21. 9.4
  22. 7.1
  23. 77
  24. 7.1
  25. 7.2
  26. 69
  27. 9.1
  28. 9.5
  29. 19
  30. 56
  31. 6.2
  32. 7.8
  33. 47
  34. 39
  35. 8.7
  36. 63
  37. 70
  38. 4.9
  39. 42
  40. 41

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