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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 927 · 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.√90 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.7 (d) 9.6
  2. 2.√59 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 8.0 (d) 7.8
  3. 3.√46 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.9 (d) 6.6
  4. 4.√24 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 5.1 (d) 4.9
  5. 5.Best estimate of 4647 ÷ 62? (a) 770 (b) 7700 (c) 77
  6. 6.Best estimate of 996 ÷ 42? (a) 250 (b) 2500 (c) 25
  7. 7.√44 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.8 (d) 6.7
  8. 8.Best estimate of 1804 ÷ 81? (a) 230 (b) 23 (c) 2300
  9. 9.√38 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.2 (d) 6.1
  10. 10.√92 to 1 decimal place? (a) 9.7 (b) 9.4 (c) 9.6 (d) 9.5
  11. 11.Best estimate of 5857 ÷ 72? (a) 840 (b) 8400 (c) 84
  12. 12.Best estimate of 2034 ÷ 32? (a) 6800 (b) 680 (c) 68
  13. 13.Best estimate of 3776 ÷ 66? (a) 54 (b) 540 (c) 5400
  14. 14.Best estimate of 4667 ÷ 79? (a) 5800 (b) 580 (c) 58
  15. 15.√78 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.8
  16. 16.Best estimate of 5315 ÷ 87? (a) 59 (b) 5900 (c) 590
  17. 17.√70 to 1 decimal place? (a) 8.5 (b) 8.2 (c) 8.3 (d) 8.4
  18. 18.Best estimate of 5296 ÷ 66? (a) 760 (b) 76 (c) 7600
  19. 19.Best estimate of 565 ÷ 28? (a) 1900 (b) 19 (c) 190
  20. 20.Best estimate of 385 ÷ 31? (a) 13 (b) 130 (c) 1300
  21. 21.Best estimate of 3337 ÷ 64? (a) 5600 (b) 560 (c) 56
  22. 22.√86 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.1 (d) 9.3
  23. 23.√42 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.7 (d) 6.4
  24. 24.√23 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.9 (d) 4.8
  25. 25.√30 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.3 (d) 5.2
  26. 26.Best estimate of 2393 ÷ 26? (a) 800 (b) 80 (c) 8000
  27. 27.Best estimate of 2461 ÷ 46? (a) 49 (b) 490 (c) 4900
  28. 28.√82 to 1 decimal place? (a) 9.1 (b) 8.8 (c) 9.0 (d) 8.9
  29. 29.Best estimate of 3029 ÷ 86? (a) 34 (b) 340 (c) 3400
  30. 30.√66 to 1 decimal place? (a) 8.2 (b) 8.1 (c) 8.3 (d) 8.0
  31. 31.√80 to 1 decimal place? (a) 8.6 (b) 8.9 (c) 8.8 (d) 8.7
  32. 32.Best estimate of 1599 ÷ 49? (a) 32 (b) 320 (c) 3200
  33. 33.Best estimate of 3955 ÷ 48? (a) 7900 (b) 79 (c) 790
  34. 34.Best estimate of 2993 ÷ 36? (a) 7500 (b) 750 (c) 75
  35. 35.√22 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 5.0 (d) 4.7
  36. 36.Best estimate of 767 ÷ 27? (a) 260 (b) 26 (c) 2600
  37. 37.√69 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.3 (d) 8.1
  38. 38.Best estimate of 1876 ÷ 52? (a) 3800 (b) 380 (c) 38
  39. 39.Best estimate of 2925 ÷ 84? (a) 370 (b) 3700 (c) 37
  40. 40.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 5.3 (d) 5.2

Answer key

  1. 9.5
  2. 7.7
  3. 6.8
  4. 4.9
  5. 77
  6. 25
  7. 6.6
  8. 23
  9. 6.2
  10. 9.6
  11. 84
  12. 68
  13. 54
  14. 58
  15. 8.8
  16. 59
  17. 8.4
  18. 76
  19. 19
  20. 13
  21. 56
  22. 9.3
  23. 6.5
  24. 4.8
  25. 5.5
  26. 80
  27. 49
  28. 9.1
  29. 34
  30. 8.1
  31. 8.9
  32. 32
  33. 79
  34. 75
  35. 4.7
  36. 26
  37. 8.3
  38. 38
  39. 37
  40. 5.1

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