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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 232 · 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.√96 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.5 (d) 9.6
  2. 2.√76 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.8 (d) 9.0
  3. 3.√41 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.2 (d) 6.4
  4. 4.Best estimate of 1932 ÷ 23? (a) 970 (b) 9700 (c) 97
  5. 5.Best estimate of 1781 ÷ 22? (a) 8900 (b) 890 (c) 89
  6. 6.√38 to 1 decimal place? (a) 6.4 (b) 6.1 (c) 6.3 (d) 6.2
  7. 7.Best estimate of 776 ÷ 46? (a) 160 (b) 16 (c) 1600
  8. 8.√29 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.3
  9. 9.Best estimate of 1912 ÷ 79? (a) 240 (b) 2400 (c) 24
  10. 10.√80 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 8.7
  11. 11.Best estimate of 1856 ÷ 57? (a) 3100 (b) 310 (c) 31
  12. 12.√46 to 1 decimal place? (a) 6.8 (b) 6.5 (c) 6.7 (d) 6.6
  13. 13.√31 to 1 decimal place? (a) 5.6 (b) 5.3 (c) 5.4 (d) 5.5
  14. 14.√51 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.0
  15. 15.Best estimate of 3440 ÷ 62? (a) 570 (b) 5700 (c) 57
  16. 16.√88 to 1 decimal place? (a) 9.4 (b) 9.1 (c) 9.2 (d) 9.3
  17. 17.Best estimate of 1325 ÷ 62? (a) 2200 (b) 220 (c) 22
  18. 18.Best estimate of 4512 ÷ 72? (a) 6400 (b) 640 (c) 64
  19. 19.Best estimate of 2049 ÷ 71? (a) 2900 (b) 29 (c) 290
  20. 20.Best estimate of 2675 ÷ 57? (a) 4500 (b) 450 (c) 45
  21. 21.Best estimate of 698 ÷ 57? (a) 1200 (b) 120 (c) 12
  22. 22.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.0 (d) 4.9
  23. 23.Best estimate of 731 ÷ 38? (a) 1800 (b) 180 (c) 18
  24. 24.√78 to 1 decimal place? (a) 8.8 (b) 8.5 (c) 8.6 (d) 8.7
  25. 25.√44 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.3 (d) 6.5
  26. 26.Best estimate of 2175 ÷ 33? (a) 73 (b) 7300 (c) 730
  27. 27.√77 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.0 (d) 9.1
  28. 28.Best estimate of 2666 ÷ 72? (a) 380 (b) 38 (c) 3800
  29. 29.√35 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 5.9 (d) 6.0
  30. 30.Best estimate of 3494 ÷ 76? (a) 440 (b) 4400 (c) 44
  31. 31.√45 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.5 (d) 6.6
  32. 32.√79 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 9.0 (d) 8.8
  33. 33.Best estimate of 3394 ÷ 39? (a) 8500 (b) 85 (c) 850
  34. 34.Best estimate of 2377 ÷ 37? (a) 5900 (b) 590 (c) 59
  35. 35.√55 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.5 (d) 7.7
  36. 36.√67 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.4
  37. 37.√52 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.2 (d) 7.3
  38. 38.Best estimate of 5072 ÷ 68? (a) 72 (b) 7200 (c) 720
  39. 39.Best estimate of 4768 ÷ 64? (a) 790 (b) 79 (c) 7900
  40. 40.Best estimate of 2830 ÷ 46? (a) 57 (b) 5700 (c) 570

Answer key

  1. 9.8
  2. 8.7
  3. 6.4
  4. 97
  5. 89
  6. 6.2
  7. 16
  8. 5.4
  9. 24
  10. 8.9
  11. 31
  12. 6.8
  13. 5.6
  14. 7.1
  15. 57
  16. 9.4
  17. 22
  18. 64
  19. 29
  20. 45
  21. 12
  22. 5.1
  23. 18
  24. 8.8
  25. 6.6
  26. 73
  27. 8.8
  28. 38
  29. 5.9
  30. 44
  31. 6.7
  32. 8.9
  33. 85
  34. 59
  35. 7.4
  36. 8.2
  37. 7.2
  38. 72
  39. 79
  40. 57

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