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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 643 · 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 3266 ÷ 67? (a) 47 (b) 470 (c) 4700
  2. 2.√84 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.4 (d) 9.2
  3. 3.√79 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 9.0 (d) 8.9
  4. 4.Best estimate of 2385 ÷ 71? (a) 34 (b) 3400 (c) 340
  5. 5.Best estimate of 4150 ÷ 52? (a) 83 (b) 830 (c) 8300
  6. 6.√40 to 1 decimal place? (a) 6.5 (b) 6.2 (c) 6.3 (d) 6.4
  7. 7.√77 to 1 decimal place? (a) 8.9 (b) 8.6 (c) 8.8 (d) 8.7
  8. 8.√42 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.4 (d) 6.5
  9. 9.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.3 (d) 8.2
  10. 10.√46 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 6.7 (d) 6.9
  11. 11.√92 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  12. 12.√53 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.5 (d) 7.6
  13. 13.√70 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.5 (d) 8.4
  14. 14.√50 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.1 (d) 7.0
  15. 15.Best estimate of 2557 ÷ 29? (a) 85 (b) 850 (c) 8500
  16. 16.√94 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.8
  17. 17.Best estimate of 1133 ÷ 56? (a) 19 (b) 190 (c) 1900
  18. 18.√28 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 5.3 (d) 5.1
  19. 19.√37 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.1 (d) 6.4
  20. 20.Best estimate of 2152 ÷ 73? (a) 3100 (b) 31 (c) 310
  21. 21.√21 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.6 (d) 4.4
  22. 22.Best estimate of 3006 ÷ 72? (a) 4300 (b) 430 (c) 43
  23. 23.Best estimate of 2193 ÷ 81? (a) 27 (b) 270 (c) 2700
  24. 24.√26 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 5.1 (d) 4.9
  25. 25.√78 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 8.8 (d) 9.0
  26. 26.Best estimate of 3308 ÷ 52? (a) 660 (b) 6600 (c) 66
  27. 27.Best estimate of 2487 ÷ 28? (a) 83 (b) 8300 (c) 830
  28. 28.√63 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 8.1
  29. 29.√65 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.2 (d) 8.3
  30. 30.√80 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 9.2 (d) 9.1
  31. 31.Best estimate of 4065 ÷ 83? (a) 5100 (b) 510 (c) 51
  32. 32.√22 to 1 decimal place? (a) 4.9 (b) 4.6 (c) 4.8 (d) 4.7
  33. 33.Best estimate of 2144 ÷ 79? (a) 27 (b) 2700 (c) 270
  34. 34.Best estimate of 2616 ÷ 29? (a) 8700 (b) 87 (c) 870
  35. 35.√30 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.3 (d) 5.6
  36. 36.Best estimate of 5635 ÷ 64? (a) 94 (b) 9400 (c) 940
  37. 37.Best estimate of 351 ÷ 22? (a) 1800 (b) 180 (c) 18
  38. 38.Best estimate of 1188 ÷ 48? (a) 24 (b) 240 (c) 2400
  39. 39.√85 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.2 (d) 9.5
  40. 40.Best estimate of 2001 ÷ 72? (a) 29 (b) 2900 (c) 290

Answer key

  1. 47
  2. 9.2
  3. 8.9
  4. 34
  5. 83
  6. 6.3
  7. 8.8
  8. 6.5
  9. 8.1
  10. 6.8
  11. 9.6
  12. 7.3
  13. 8.4
  14. 7.1
  15. 85
  16. 9.7
  17. 19
  18. 5.3
  19. 6.1
  20. 31
  21. 4.6
  22. 43
  23. 27
  24. 5.1
  25. 8.8
  26. 66
  27. 83
  28. 7.9
  29. 8.1
  30. 8.9
  31. 51
  32. 4.7
  33. 27
  34. 87
  35. 5.5
  36. 94
  37. 18
  38. 24
  39. 9.2
  40. 29

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