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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 361 · 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 2700 ÷ 58? (a) 450 (b) 45 (c) 4500
  2. 2.√79 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.9 (d) 8.8
  3. 3.Best estimate of 1570 ÷ 29? (a) 52 (b) 5200 (c) 520
  4. 4.Best estimate of 900 ÷ 32? (a) 3000 (b) 300 (c) 30
  5. 5.√77 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.9 (d) 8.8
  6. 6.Best estimate of 7348 ÷ 78? (a) 92 (b) 920 (c) 9200
  7. 7.√34 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 5.9 (d) 5.8
  8. 8.Best estimate of 2161 ÷ 27? (a) 72 (b) 7200 (c) 720
  9. 9.√22 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.7 (d) 4.8
  10. 10.Best estimate of 709 ÷ 24? (a) 35 (b) 350 (c) 3500
  11. 11.Best estimate of 4993 ÷ 69? (a) 71 (b) 7100 (c) 710
  12. 12.Best estimate of 5821 ÷ 77? (a) 730 (b) 73 (c) 7300
  13. 13.Best estimate of 2496 ÷ 82? (a) 3100 (b) 31 (c) 310
  14. 14.√20 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.3 (d) 4.4
  15. 15.Best estimate of 1769 ÷ 78? (a) 2200 (b) 22 (c) 220
  16. 16.√61 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.5
  17. 17.√65 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.0 (d) 8.2
  18. 18.√24 to 1 decimal place? (a) 4.7 (b) 4.8 (c) 5.0 (d) 4.9
  19. 19.Best estimate of 6491 ÷ 87? (a) 7200 (b) 72 (c) 720
  20. 20.√80 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 8.9 (d) 9.1
  21. 21.√75 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 8.6
  22. 22.√51 to 1 decimal place? (a) 7.1 (b) 6.8 (c) 6.9 (d) 7.0
  23. 23.√84 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.0
  24. 24.√88 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.4
  25. 25.√62 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 7.9 (d) 8.1
  26. 26.Best estimate of 1715 ÷ 86? (a) 1900 (b) 190 (c) 19
  27. 27.Best estimate of 400 ÷ 32? (a) 13 (b) 1300 (c) 130
  28. 28.Best estimate of 1124 ÷ 56? (a) 19 (b) 190 (c) 1900
  29. 29.Best estimate of 1899 ÷ 66? (a) 270 (b) 2700 (c) 27
  30. 30.√63 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 7.9 (d) 8.1
  31. 31.Best estimate of 2186 ÷ 38? (a) 5500 (b) 550 (c) 55
  32. 32.√72 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.4 (d) 8.7
  33. 33.Best estimate of 3180 ÷ 42? (a) 80 (b) 8000 (c) 800
  34. 34.Best estimate of 806 ÷ 42? (a) 200 (b) 2000 (c) 20
  35. 35.Best estimate of 2087 ÷ 86? (a) 230 (b) 23 (c) 2300
  36. 36.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.0
  37. 37.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.7
  38. 38.Best estimate of 3578 ÷ 56? (a) 600 (b) 6000 (c) 60
  39. 39.Best estimate of 1513 ÷ 23? (a) 7600 (b) 76 (c) 760
  40. 40.Best estimate of 1965 ÷ 37? (a) 490 (b) 49 (c) 4900

Answer key

  1. 45
  2. 8.9
  3. 52
  4. 30
  5. 8.8
  6. 92
  7. 5.8
  8. 72
  9. 4.7
  10. 35
  11. 71
  12. 73
  13. 31
  14. 4.5
  15. 22
  16. 7.8
  17. 8.1
  18. 4.9
  19. 72
  20. 8.9
  21. 8.7
  22. 7.1
  23. 9.2
  24. 9.4
  25. 7.9
  26. 19
  27. 13
  28. 19
  29. 27
  30. 7.9
  31. 55
  32. 8.5
  33. 80
  34. 20
  35. 23
  36. 5.1
  37. 7.6
  38. 60
  39. 76
  40. 49

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