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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 729 · 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 510 ÷ 21? (a) 260 (b) 26 (c) 2600
  2. 2.Best estimate of 5930 ÷ 86? (a) 6600 (b) 660 (c) 66
  3. 3.√20 to 1 decimal place? (a) 4.3 (b) 4.2 (c) 4.4 (d) 4.5
  4. 4.Best estimate of 5717 ÷ 84? (a) 710 (b) 7100 (c) 71
  5. 5.√47 to 1 decimal place? (a) 6.9 (b) 7.2 (c) 7.1 (d) 7.0
  6. 6.√28 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.2 (d) 5.0
  7. 7.Best estimate of 3530 ÷ 56? (a) 59 (b) 5900 (c) 590
  8. 8.Best estimate of 2017 ÷ 24? (a) 10100 (b) 1010 (c) 101
  9. 9.Best estimate of 2239 ÷ 27? (a) 750 (b) 75 (c) 7500
  10. 10.√34 to 1 decimal place? (a) 5.9 (b) 6.1 (c) 6.0 (d) 5.8
  11. 11.Best estimate of 1170 ÷ 36? (a) 290 (b) 29 (c) 2900
  12. 12.Best estimate of 2622 ÷ 34? (a) 8700 (b) 87 (c) 870
  13. 13.√31 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.7 (d) 5.4
  14. 14.Best estimate of 953 ÷ 49? (a) 190 (b) 19 (c) 1900
  15. 15.√22 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.8 (d) 4.6
  16. 16.Best estimate of 2008 ÷ 26? (a) 6700 (b) 67 (c) 670
  17. 17.√43 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.7 (d) 6.9
  18. 18.Best estimate of 4310 ÷ 74? (a) 620 (b) 62 (c) 6200
  19. 19.Best estimate of 3264 ÷ 62? (a) 5400 (b) 54 (c) 540
  20. 20.Best estimate of 1872 ÷ 42? (a) 4700 (b) 470 (c) 47
  21. 21.Best estimate of 3822 ÷ 68? (a) 5500 (b) 55 (c) 550
  22. 22.√32 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.8 (d) 5.7
  23. 23.√58 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.6 (d) 7.7
  24. 24.Best estimate of 2071 ÷ 82? (a) 260 (b) 26 (c) 2600
  25. 25.Best estimate of 2180 ÷ 26? (a) 7300 (b) 730 (c) 73
  26. 26.√55 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.4 (d) 7.3
  27. 27.√72 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.6
  28. 28.Best estimate of 1027 ÷ 46? (a) 210 (b) 21 (c) 2100
  29. 29.Best estimate of 2306 ÷ 34? (a) 7700 (b) 770 (c) 77
  30. 30.Best estimate of 2602 ÷ 77? (a) 330 (b) 3300 (c) 33
  31. 31.Best estimate of 1626 ÷ 24? (a) 810 (b) 8100 (c) 81
  32. 32.Best estimate of 1238 ÷ 49? (a) 250 (b) 2500 (c) 25
  33. 33.Best estimate of 5032 ÷ 66? (a) 7200 (b) 720 (c) 72
  34. 34.√61 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.9 (d) 7.8
  35. 35.Best estimate of 1884 ÷ 22? (a) 94 (b) 940 (c) 9400
  36. 36.Best estimate of 1672 ÷ 36? (a) 420 (b) 42 (c) 4200
  37. 37.Best estimate of 4632 ÷ 52? (a) 930 (b) 9300 (c) 93
  38. 38.√44 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.7 (d) 6.9
  39. 39.√59 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.5 (d) 7.4
  40. 40.√24 to 1 decimal place? (a) 4.6 (b) 4.9 (c) 4.8 (d) 4.7

Answer key

  1. 26
  2. 66
  3. 4.5
  4. 71
  5. 6.9
  6. 5.3
  7. 59
  8. 101
  9. 75
  10. 5.8
  11. 29
  12. 87
  13. 5.6
  14. 19
  15. 4.7
  16. 67
  17. 6.6
  18. 62
  19. 54
  20. 47
  21. 55
  22. 5.7
  23. 7.6
  24. 26
  25. 73
  26. 7.4
  27. 8.5
  28. 21
  29. 77
  30. 33
  31. 81
  32. 25
  33. 72
  34. 7.8
  35. 94
  36. 42
  37. 93
  38. 6.6
  39. 7.7
  40. 4.9

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