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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 20 · 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 1767 ÷ 34? (a) 59 (b) 5900 (c) 590
  2. 2.Best estimate of 1780 ÷ 22? (a) 890 (b) 89 (c) 8900
  3. 3.Best estimate of 5441 ÷ 71? (a) 78 (b) 7800 (c) 780
  4. 4.√80 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.1 (d) 9.0
  5. 5.Best estimate of 1767 ÷ 81? (a) 2200 (b) 22 (c) 220
  6. 6.Best estimate of 4435 ÷ 73? (a) 630 (b) 6300 (c) 63
  7. 7.√89 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.6
  8. 8.√41 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.6 (d) 6.5
  9. 9.Best estimate of 5998 ÷ 82? (a) 7500 (b) 75 (c) 750
  10. 10.Best estimate of 3310 ÷ 74? (a) 47 (b) 470 (c) 4700
  11. 11.√79 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.2 (d) 9.1
  12. 12.√29 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.5 (d) 5.3
  13. 13.√74 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.6 (d) 8.7
  14. 14.√34 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.8 (d) 5.7
  15. 15.Best estimate of 2426 ÷ 69? (a) 3500 (b) 35 (c) 350
  16. 16.Best estimate of 2159 ÷ 42? (a) 540 (b) 5400 (c) 54
  17. 17.Best estimate of 4044 ÷ 78? (a) 510 (b) 5100 (c) 51
  18. 18.√26 to 1 decimal place? (a) 5.0 (b) 5.3 (c) 5.1 (d) 5.2
  19. 19.Best estimate of 4344 ÷ 52? (a) 87 (b) 870 (c) 8700
  20. 20.√84 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.2 (d) 9.4
  21. 21.√82 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.0 (d) 9.1
  22. 22.Best estimate of 1625 ÷ 84? (a) 20 (b) 2000 (c) 200
  23. 23.Best estimate of 3538 ÷ 39? (a) 8800 (b) 880 (c) 88
  24. 24.√94 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.4
  25. 25.Best estimate of 1125 ÷ 61? (a) 190 (b) 1900 (c) 19
  26. 26.Best estimate of 6526 ÷ 83? (a) 82 (b) 820 (c) 8200
  27. 27.√72 to 1 decimal place? (a) 8.5 (b) 8.2 (c) 8.3 (d) 8.4
  28. 28.√45 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 6.7 (d) 6.9
  29. 29.√67 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.5 (d) 8.3
  30. 30.Best estimate of 500 ÷ 26? (a) 170 (b) 1700 (c) 17
  31. 31.Best estimate of 3389 ÷ 42? (a) 8500 (b) 850 (c) 85
  32. 32.Best estimate of 2133 ÷ 29? (a) 710 (b) 71 (c) 7100
  33. 33.√27 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.0 (d) 5.3
  34. 34.√75 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  35. 35.Best estimate of 3367 ÷ 86? (a) 3700 (b) 37 (c) 370
  36. 36.Best estimate of 4560 ÷ 72? (a) 650 (b) 65 (c) 6500
  37. 37.√92 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 9.6
  38. 38.Best estimate of 1920 ÷ 37? (a) 4800 (b) 480 (c) 48
  39. 39.Best estimate of 3591 ÷ 71? (a) 51 (b) 5100 (c) 510
  40. 40.Best estimate of 2538 ÷ 66? (a) 36 (b) 3600 (c) 360

Answer key

  1. 59
  2. 89
  3. 78
  4. 8.9
  5. 22
  6. 63
  7. 9.4
  8. 6.4
  9. 75
  10. 47
  11. 8.9
  12. 5.4
  13. 8.6
  14. 5.8
  15. 35
  16. 54
  17. 51
  18. 5.1
  19. 87
  20. 9.2
  21. 9.1
  22. 20
  23. 88
  24. 9.7
  25. 19
  26. 82
  27. 8.5
  28. 6.7
  29. 8.2
  30. 17
  31. 85
  32. 71
  33. 5.2
  34. 8.7
  35. 37
  36. 65
  37. 9.6
  38. 48
  39. 51
  40. 36

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