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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 430 · 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 2597 ÷ 54? (a) 5200 (b) 520 (c) 52
  2. 2.Best estimate of 3796 ÷ 49? (a) 7600 (b) 760 (c) 76
  3. 3.√55 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.6 (d) 7.4
  4. 4.Best estimate of 1415 ÷ 44? (a) 3500 (b) 350 (c) 35
  5. 5.√69 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.3 (d) 8.0
  6. 6.√94 to 1 decimal place? (a) 10.0 (b) 9.7 (c) 9.8 (d) 9.9
  7. 7.√65 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.1
  8. 8.√63 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.8 (d) 7.6
  9. 9.√45 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 6.7 (d) 6.9
  10. 10.Best estimate of 1884 ÷ 71? (a) 27 (b) 270 (c) 2700
  11. 11.Best estimate of 1450 ÷ 72? (a) 210 (b) 2100 (c) 21
  12. 12.√66 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 8.2
  13. 13.Best estimate of 951 ÷ 34? (a) 3200 (b) 320 (c) 32
  14. 14.√29 to 1 decimal place? (a) 5.4 (b) 5.7 (c) 5.5 (d) 5.6
  15. 15.√26 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 4.8 (d) 4.9
  16. 16.√51 to 1 decimal place? (a) 7.1 (b) 7.4 (c) 7.3 (d) 7.2
  17. 17.Best estimate of 914 ÷ 24? (a) 460 (b) 46 (c) 4600
  18. 18.Best estimate of 1578 ÷ 39? (a) 390 (b) 39 (c) 3900
  19. 19.Best estimate of 2696 ÷ 79? (a) 340 (b) 3400 (c) 34
  20. 20.Best estimate of 5015 ÷ 58? (a) 8400 (b) 840 (c) 84
  21. 21.Best estimate of 2790 ÷ 56? (a) 470 (b) 4700 (c) 47
  22. 22.Best estimate of 1053 ÷ 63? (a) 1800 (b) 18 (c) 180
  23. 23.Best estimate of 1095 ÷ 39? (a) 27 (b) 270 (c) 2700
  24. 24.Best estimate of 7877 ÷ 89? (a) 880 (b) 8800 (c) 88
  25. 25.Best estimate of 6098 ÷ 67? (a) 8700 (b) 87 (c) 870
  26. 26.Best estimate of 4621 ÷ 64? (a) 770 (b) 77 (c) 7700
  27. 27.√84 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.1
  28. 28.√61 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  29. 29.√44 to 1 decimal place? (a) 6.9 (b) 6.6 (c) 6.7 (d) 6.8
  30. 30.Best estimate of 2478 ÷ 72? (a) 3500 (b) 35 (c) 350
  31. 31.√74 to 1 decimal place? (a) 8.5 (b) 8.8 (c) 8.6 (d) 8.7
  32. 32.Best estimate of 3246 ÷ 38? (a) 8100 (b) 81 (c) 810
  33. 33.√58 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.9
  34. 34.Best estimate of 1360 ÷ 47? (a) 27 (b) 2700 (c) 270
  35. 35.√67 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.4 (d) 8.3
  36. 36.√77 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 9.1
  37. 37.Best estimate of 1309 ÷ 46? (a) 2600 (b) 260 (c) 26
  38. 38.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.6 (d) 8.5
  39. 39.Best estimate of 599 ÷ 28? (a) 20 (b) 2000 (c) 200
  40. 40.Best estimate of 4690 ÷ 56? (a) 7800 (b) 780 (c) 78

Answer key

  1. 52
  2. 76
  3. 7.4
  4. 35
  5. 8.3
  6. 9.7
  7. 8.1
  8. 7.9
  9. 6.7
  10. 27
  11. 21
  12. 8.1
  13. 32
  14. 5.4
  15. 5.1
  16. 7.1
  17. 46
  18. 39
  19. 34
  20. 84
  21. 47
  22. 18
  23. 27
  24. 88
  25. 87
  26. 77
  27. 9.2
  28. 7.8
  29. 6.6
  30. 35
  31. 8.6
  32. 81
  33. 7.6
  34. 27
  35. 8.2
  36. 8.8
  37. 26
  38. 8.4
  39. 20
  40. 78

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