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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 308 · 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.√94 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  2. 2.Best estimate of 1196 ÷ 26? (a) 400 (b) 4000 (c) 40
  3. 3.Best estimate of 3092 ÷ 46? (a) 62 (b) 620 (c) 6200
  4. 4.Best estimate of 343 ÷ 26? (a) 11 (b) 110 (c) 1100
  5. 5.Best estimate of 2784 ÷ 88? (a) 31 (b) 310 (c) 3100
  6. 6.√26 to 1 decimal place? (a) 4.9 (b) 5.2 (c) 5.1 (d) 5.0
  7. 7.Best estimate of 388 ÷ 22? (a) 1900 (b) 19 (c) 190
  8. 8.Best estimate of 5913 ÷ 89? (a) 660 (b) 6600 (c) 66
  9. 9.√82 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.4
  10. 10.√35 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.8 (d) 5.9
  11. 11.Best estimate of 2141 ÷ 73? (a) 31 (b) 3100 (c) 310
  12. 12.Best estimate of 3540 ÷ 68? (a) 5100 (b) 51 (c) 510
  13. 13.√92 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.6 (d) 9.3
  14. 14.√55 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.2 (d) 7.3
  15. 15.Best estimate of 4197 ÷ 74? (a) 6000 (b) 60 (c) 600
  16. 16.Best estimate of 595 ÷ 32? (a) 20 (b) 2000 (c) 200
  17. 17.Best estimate of 522 ÷ 32? (a) 170 (b) 1700 (c) 17
  18. 18.√85 to 1 decimal place? (a) 9.0 (b) 9.3 (c) 9.2 (d) 9.1
  19. 19.√46 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 6.9 (d) 7.1
  20. 20.Best estimate of 1970 ÷ 71? (a) 280 (b) 2800 (c) 28
  21. 21.Best estimate of 5247 ÷ 56? (a) 8700 (b) 870 (c) 87
  22. 22.Best estimate of 335 ÷ 23? (a) 170 (b) 1700 (c) 17
  23. 23.√37 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.4 (d) 6.1
  24. 24.Best estimate of 8034 ÷ 86? (a) 89 (b) 890 (c) 8900
  25. 25.Best estimate of 4786 ÷ 73? (a) 680 (b) 68 (c) 6800
  26. 26.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 7.9 (d) 8.2
  27. 27.√75 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.9 (d) 8.7
  28. 28.Best estimate of 6083 ÷ 66? (a) 87 (b) 8700 (c) 870
  29. 29.√45 to 1 decimal place? (a) 6.6 (b) 6.9 (c) 6.8 (d) 6.7
  30. 30.√52 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.0 (d) 7.1
  31. 31.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.6
  32. 32.Best estimate of 1299 ÷ 36? (a) 320 (b) 3200 (c) 32
  33. 33.Best estimate of 1106 ÷ 32? (a) 370 (b) 3700 (c) 37
  34. 34.√21 to 1 decimal place? (a) 4.6 (b) 4.4 (c) 4.7 (d) 4.5
  35. 35.√76 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 8.7
  36. 36.√32 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.4 (d) 5.6
  37. 37.Best estimate of 2358 ÷ 37? (a) 5900 (b) 59 (c) 590
  38. 38.√51 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.2 (d) 7.4
  39. 39.Best estimate of 483 ÷ 36? (a) 120 (b) 1200 (c) 12
  40. 40.√34 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.0 (d) 5.8

Answer key

  1. 9.7
  2. 40
  3. 62
  4. 11
  5. 31
  6. 5.1
  7. 19
  8. 66
  9. 9.1
  10. 5.9
  11. 31
  12. 51
  13. 9.6
  14. 7.4
  15. 60
  16. 20
  17. 17
  18. 9.2
  19. 6.8
  20. 28
  21. 87
  22. 17
  23. 6.1
  24. 89
  25. 68
  26. 8.1
  27. 8.7
  28. 87
  29. 6.7
  30. 7.2
  31. 6.3
  32. 32
  33. 37
  34. 4.6
  35. 8.7
  36. 5.7
  37. 59
  38. 7.1
  39. 12
  40. 5.8

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