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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 903 · 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 2633 ÷ 39? (a) 6600 (b) 660 (c) 66
  2. 2.Best estimate of 1748 ÷ 22? (a) 87 (b) 8700 (c) 870
  3. 3.Best estimate of 1877 ÷ 27? (a) 630 (b) 6300 (c) 63
  4. 4.√82 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.1 (d) 9.2
  5. 5.Best estimate of 2506 ÷ 53? (a) 50 (b) 5000 (c) 500
  6. 6.√26 to 1 decimal place? (a) 5.1 (b) 5.4 (c) 5.3 (d) 5.2
  7. 7.Best estimate of 313 ÷ 24? (a) 1600 (b) 160 (c) 16
  8. 8.Best estimate of 1397 ÷ 29? (a) 4700 (b) 47 (c) 470
  9. 9.Best estimate of 1835 ÷ 38? (a) 4600 (b) 46 (c) 460
  10. 10.Best estimate of 2404 ÷ 42? (a) 60 (b) 600 (c) 6000
  11. 11.Best estimate of 3325 ÷ 46? (a) 670 (b) 67 (c) 6700
  12. 12.Best estimate of 4062 ÷ 51? (a) 81 (b) 810 (c) 8100
  13. 13.Best estimate of 926 ÷ 32? (a) 310 (b) 3100 (c) 31
  14. 14.Best estimate of 2854 ÷ 59? (a) 48 (b) 4800 (c) 480
  15. 15.Best estimate of 2625 ÷ 52? (a) 530 (b) 5300 (c) 53
  16. 16.√24 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.8 (d) 4.7
  17. 17.Best estimate of 1457 ÷ 78? (a) 180 (b) 1800 (c) 18
  18. 18.√21 to 1 decimal place? (a) 4.5 (b) 4.8 (c) 4.7 (d) 4.6
  19. 19.√51 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 7.1 (d) 6.9
  20. 20.√34 to 1 decimal place? (a) 6.1 (b) 5.8 (c) 6.0 (d) 5.9
  21. 21.√22 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.4 (d) 4.5
  22. 22.√92 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.7
  23. 23.√89 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.5 (d) 9.6
  24. 24.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.7
  25. 25.Best estimate of 3606 ÷ 72? (a) 52 (b) 520 (c) 5200
  26. 26.√98 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 10.0 (d) 9.9
  27. 27.Best estimate of 1977 ÷ 36? (a) 4900 (b) 490 (c) 49
  28. 28.Best estimate of 327 ÷ 24? (a) 160 (b) 1600 (c) 16
  29. 29.√28 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  30. 30.Best estimate of 785 ÷ 21? (a) 390 (b) 3900 (c) 39
  31. 31.√43 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.5 (d) 6.4
  32. 32.√52 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.2 (d) 7.3
  33. 33.Best estimate of 1524 ÷ 47? (a) 300 (b) 30 (c) 3000
  34. 34.Best estimate of 1789 ÷ 62? (a) 300 (b) 3000 (c) 30
  35. 35.Best estimate of 2066 ÷ 39? (a) 52 (b) 5200 (c) 520
  36. 36.Best estimate of 2716 ÷ 56? (a) 45 (b) 450 (c) 4500
  37. 37.Best estimate of 2847 ÷ 77? (a) 360 (b) 3600 (c) 36
  38. 38.Best estimate of 1887 ÷ 22? (a) 940 (b) 9400 (c) 94
  39. 39.√47 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 6.9 (d) 7.1
  40. 40.Best estimate of 1280 ÷ 32? (a) 43 (b) 430 (c) 4300

Answer key

  1. 66
  2. 87
  3. 63
  4. 9.1
  5. 50
  6. 5.1
  7. 16
  8. 47
  9. 46
  10. 60
  11. 67
  12. 81
  13. 31
  14. 48
  15. 53
  16. 4.9
  17. 18
  18. 4.6
  19. 7.1
  20. 5.8
  21. 4.7
  22. 9.6
  23. 9.4
  24. 7.6
  25. 52
  26. 9.9
  27. 49
  28. 16
  29. 5.3
  30. 39
  31. 6.6
  32. 7.2
  33. 30
  34. 30
  35. 52
  36. 45
  37. 36
  38. 94
  39. 6.9
  40. 43

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