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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 162 · 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 7077 ÷ 89? (a) 7900 (b) 790 (c) 79
  2. 2.√55 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.2 (d) 7.4
  3. 3.Best estimate of 2689 ÷ 39? (a) 670 (b) 6700 (c) 67
  4. 4.√77 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.7 (d) 8.5
  5. 5.Best estimate of 887 ÷ 26? (a) 3000 (b) 300 (c) 30
  6. 6.√32 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 5.7 (d) 6.0
  7. 7.√61 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 7.9 (d) 7.8
  8. 8.√51 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.2 (d) 7.4
  9. 9.Best estimate of 1154 ÷ 46? (a) 2300 (b) 230 (c) 23
  10. 10.Best estimate of 3182 ÷ 68? (a) 45 (b) 4500 (c) 450
  11. 11.Best estimate of 1893 ÷ 86? (a) 2100 (b) 21 (c) 210
  12. 12.Best estimate of 2120 ÷ 88? (a) 2400 (b) 24 (c) 240
  13. 13.Best estimate of 1526 ÷ 72? (a) 22 (b) 220 (c) 2200
  14. 14.Best estimate of 4952 ÷ 73? (a) 710 (b) 7100 (c) 71
  15. 15.√34 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 5.9 (d) 5.7
  16. 16.Best estimate of 1217 ÷ 62? (a) 2000 (b) 200 (c) 20
  17. 17.Best estimate of 2953 ÷ 84? (a) 3700 (b) 370 (c) 37
  18. 18.Best estimate of 337 ÷ 24? (a) 17 (b) 1700 (c) 170
  19. 19.√26 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.4 (d) 5.3
  20. 20.Best estimate of 5136 ÷ 88? (a) 57 (b) 5700 (c) 570
  21. 21.√42 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.7 (d) 6.5
  22. 22.√23 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 4.8 (d) 5.0
  23. 23.Best estimate of 712 ÷ 36? (a) 1800 (b) 18 (c) 180
  24. 24.Best estimate of 4717 ÷ 51? (a) 94 (b) 9400 (c) 940
  25. 25.√62 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.9 (d) 8.0
  26. 26.√72 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.7
  27. 27.√63 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.9 (d) 7.6
  28. 28.√31 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.4 (d) 5.3
  29. 29.√45 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.8 (d) 6.7
  30. 30.√92 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.9 (d) 9.7
  31. 31.Best estimate of 1986 ÷ 26? (a) 660 (b) 6600 (c) 66
  32. 32.Best estimate of 1134 ÷ 74? (a) 1600 (b) 160 (c) 16
  33. 33.Best estimate of 2088 ÷ 67? (a) 3000 (b) 30 (c) 300
  34. 34.√79 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 8.7
  35. 35.√94 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 9.7
  36. 36.Best estimate of 1143 ÷ 64? (a) 190 (b) 19 (c) 1900
  37. 37.Best estimate of 4838 ÷ 53? (a) 970 (b) 9700 (c) 97
  38. 38.√47 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  39. 39.Best estimate of 4751 ÷ 64? (a) 790 (b) 7900 (c) 79
  40. 40.Best estimate of 5823 ÷ 78? (a) 730 (b) 73 (c) 7300

Answer key

  1. 79
  2. 7.4
  3. 67
  4. 8.8
  5. 30
  6. 5.7
  7. 7.8
  8. 7.1
  9. 23
  10. 45
  11. 21
  12. 24
  13. 22
  14. 71
  15. 5.8
  16. 20
  17. 37
  18. 17
  19. 5.1
  20. 57
  21. 6.5
  22. 4.8
  23. 18
  24. 94
  25. 7.9
  26. 8.5
  27. 7.9
  28. 5.6
  29. 6.7
  30. 9.6
  31. 66
  32. 16
  33. 30
  34. 8.9
  35. 9.7
  36. 19
  37. 97
  38. 6.9
  39. 79
  40. 73

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