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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 683 · 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.√31 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.6 (d) 5.5
  2. 2.√40 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.0 (d) 6.3
  3. 3.Best estimate of 934 ÷ 49? (a) 190 (b) 19 (c) 1900
  4. 4.Best estimate of 554 ÷ 26? (a) 180 (b) 1800 (c) 18
  5. 5.Best estimate of 1523 ÷ 36? (a) 3800 (b) 38 (c) 380
  6. 6.√61 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 8.0 (d) 7.8
  7. 7.√24 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 4.9 (d) 5.0
  8. 8.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.3 (d) 7.4
  9. 9.√65 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.1 (d) 8.3
  10. 10.√86 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.2
  11. 11.Best estimate of 4199 ÷ 73? (a) 600 (b) 6000 (c) 60
  12. 12.Best estimate of 728 ÷ 28? (a) 2400 (b) 240 (c) 24
  13. 13.√96 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 10.0 (d) 9.8
  14. 14.√48 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.9 (d) 6.8
  15. 15.Best estimate of 3474 ÷ 81? (a) 430 (b) 4300 (c) 43
  16. 16.√32 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.6 (d) 5.8
  17. 17.√76 to 1 decimal place? (a) 8.6 (b) 8.9 (c) 8.8 (d) 8.7
  18. 18.√28 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.2 (d) 5.0
  19. 19.√41 to 1 decimal place? (a) 6.6 (b) 6.5 (c) 6.4 (d) 6.7
  20. 20.√98 to 1 decimal place? (a) 10.0 (b) 10.2 (c) 9.9 (d) 10.1
  21. 21.Best estimate of 3963 ÷ 58? (a) 6600 (b) 66 (c) 660
  22. 22.√84 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.2
  23. 23.Best estimate of 5084 ÷ 59? (a) 850 (b) 8500 (c) 85
  24. 24.Best estimate of 3262 ÷ 47? (a) 65 (b) 6500 (c) 650
  25. 25.√89 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.5 (d) 9.4
  26. 26.√52 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 6.9 (d) 7.0
  27. 27.Best estimate of 992 ÷ 27? (a) 3300 (b) 33 (c) 330
  28. 28.Best estimate of 3991 ÷ 67? (a) 57 (b) 570 (c) 5700
  29. 29.√29 to 1 decimal place? (a) 5.7 (b) 5.4 (c) 5.5 (d) 5.6
  30. 30.√55 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.6 (d) 7.4
  31. 31.Best estimate of 754 ÷ 38? (a) 190 (b) 1900 (c) 19
  32. 32.Best estimate of 1103 ÷ 38? (a) 280 (b) 28 (c) 2800
  33. 33.Best estimate of 488 ÷ 28? (a) 16 (b) 1600 (c) 160
  34. 34.Best estimate of 3442 ÷ 42? (a) 86 (b) 8600 (c) 860
  35. 35.Best estimate of 3222 ÷ 64? (a) 540 (b) 5400 (c) 54
  36. 36.Best estimate of 697 ÷ 23? (a) 3500 (b) 350 (c) 35
  37. 37.√79 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 8.8 (d) 9.0
  38. 38.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.8 (d) 9.7
  39. 39.Best estimate of 676 ÷ 21? (a) 340 (b) 34 (c) 3400
  40. 40.√62 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8

Answer key

  1. 5.6
  2. 6.3
  3. 19
  4. 18
  5. 38
  6. 7.8
  7. 4.9
  8. 7.6
  9. 8.1
  10. 9.3
  11. 60
  12. 24
  13. 9.8
  14. 6.9
  15. 43
  16. 5.7
  17. 8.7
  18. 5.3
  19. 6.4
  20. 9.9
  21. 66
  22. 9.2
  23. 85
  24. 65
  25. 9.4
  26. 7.2
  27. 33
  28. 57
  29. 5.4
  30. 7.4
  31. 19
  32. 28
  33. 16
  34. 86
  35. 54
  36. 35
  37. 8.9
  38. 9.5
  39. 34
  40. 7.9

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