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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 435 · 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.√47 to 1 decimal place? (a) 6.9 (b) 7.2 (c) 7.0 (d) 7.1
  2. 2.√96 to 1 decimal place? (a) 9.8 (b) 9.5 (c) 9.7 (d) 9.6
  3. 3.Best estimate of 896 ÷ 24? (a) 45 (b) 450 (c) 4500
  4. 4.√42 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.7
  5. 5.Best estimate of 1949 ÷ 29? (a) 6500 (b) 65 (c) 650
  6. 6.√41 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.7 (d) 6.4
  7. 7.Best estimate of 2324 ÷ 31? (a) 77 (b) 770 (c) 7700
  8. 8.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 5.9 (d) 6.0
  9. 9.Best estimate of 1642 ÷ 59? (a) 27 (b) 2700 (c) 270
  10. 10.√34 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 6.0 (d) 5.8
  11. 11.Best estimate of 1096 ÷ 52? (a) 2200 (b) 22 (c) 220
  12. 12.Best estimate of 4174 ÷ 64? (a) 70 (b) 700 (c) 7000
  13. 13.√43 to 1 decimal place? (a) 6.5 (b) 6.8 (c) 6.7 (d) 6.6
  14. 14.√29 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.2 (d) 5.4
  15. 15.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.0
  16. 16.√86 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  17. 17.Best estimate of 3505 ÷ 38? (a) 88 (b) 8800 (c) 880
  18. 18.√72 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.5 (d) 8.6
  19. 19.√23 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 5.0
  20. 20.Best estimate of 2192 ÷ 86? (a) 24 (b) 240 (c) 2400
  21. 21.Best estimate of 2395 ÷ 68? (a) 3400 (b) 34 (c) 340
  22. 22.√56 to 1 decimal place? (a) 7.5 (b) 7.2 (c) 7.4 (d) 7.3
  23. 23.√66 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.1 (d) 8.3
  24. 24.√21 to 1 decimal place? (a) 4.9 (b) 4.6 (c) 4.8 (d) 4.7
  25. 25.Best estimate of 5710 ÷ 62? (a) 9500 (b) 95 (c) 950
  26. 26.Best estimate of 4025 ÷ 46? (a) 810 (b) 81 (c) 8100
  27. 27.Best estimate of 1332 ÷ 49? (a) 270 (b) 27 (c) 2700
  28. 28.√98 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  29. 29.Best estimate of 3496 ÷ 56? (a) 5800 (b) 580 (c) 58
  30. 30.Best estimate of 3497 ÷ 68? (a) 50 (b) 500 (c) 5000
  31. 31.√67 to 1 decimal place? (a) 8.0 (b) 8.3 (c) 8.1 (d) 8.2
  32. 32.Best estimate of 1528 ÷ 46? (a) 31 (b) 310 (c) 3100
  33. 33.√61 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  34. 34.√40 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.0 (d) 6.1
  35. 35.√20 to 1 decimal place? (a) 4.5 (b) 4.8 (c) 4.7 (d) 4.6
  36. 36.Best estimate of 4389 ÷ 81? (a) 55 (b) 5500 (c) 550
  37. 37.√71 to 1 decimal place? (a) 8.3 (b) 8.6 (c) 8.5 (d) 8.4
  38. 38.√48 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 7.0 (d) 6.9
  39. 39.√51 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 7.0 (d) 7.1
  40. 40.Best estimate of 4816 ÷ 56? (a) 8000 (b) 800 (c) 80

Answer key

  1. 6.9
  2. 9.8
  3. 45
  4. 6.5
  5. 65
  6. 6.4
  7. 77
  8. 6.1
  9. 27
  10. 5.8
  11. 22
  12. 70
  13. 6.6
  14. 5.4
  15. 9.1
  16. 9.3
  17. 88
  18. 8.5
  19. 4.8
  20. 24
  21. 34
  22. 7.5
  23. 8.1
  24. 4.6
  25. 95
  26. 81
  27. 27
  28. 9.9
  29. 58
  30. 50
  31. 8.2
  32. 31
  33. 7.8
  34. 6.3
  35. 4.5
  36. 55
  37. 8.4
  38. 6.9
  39. 7.1
  40. 80

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