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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 815 · 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 4736 ÷ 72? (a) 6800 (b) 68 (c) 680
  2. 2.Best estimate of 5934 ÷ 66? (a) 85 (b) 8500 (c) 850
  3. 3.Best estimate of 5996 ÷ 83? (a) 75 (b) 750 (c) 7500
  4. 4.Best estimate of 1134 ÷ 42? (a) 280 (b) 28 (c) 2800
  5. 5.Best estimate of 531 ÷ 37? (a) 130 (b) 1300 (c) 13
  6. 6.√61 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.8 (d) 7.5
  7. 7.√87 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.3 (d) 9.4
  8. 8.√83 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 9.1
  9. 9.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 10.1
  10. 10.√46 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.6 (d) 6.7
  11. 11.Best estimate of 2138 ÷ 49? (a) 4300 (b) 430 (c) 43
  12. 12.√58 to 1 decimal place? (a) 7.3 (b) 7.6 (c) 7.4 (d) 7.5
  13. 13.Best estimate of 2452 ÷ 82? (a) 3100 (b) 31 (c) 310
  14. 14.Best estimate of 865 ÷ 66? (a) 12 (b) 1200 (c) 120
  15. 15.Best estimate of 1176 ÷ 38? (a) 2900 (b) 29 (c) 290
  16. 16.√72 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.5
  17. 17.Best estimate of 4196 ÷ 66? (a) 60 (b) 6000 (c) 600
  18. 18.Best estimate of 4579 ÷ 69? (a) 65 (b) 650 (c) 6500
  19. 19.Best estimate of 2091 ÷ 26? (a) 7000 (b) 700 (c) 70
  20. 20.Best estimate of 2261 ÷ 28? (a) 750 (b) 75 (c) 7500
  21. 21.Best estimate of 2137 ÷ 66? (a) 310 (b) 3100 (c) 31
  22. 22.Best estimate of 4472 ÷ 62? (a) 7500 (b) 750 (c) 75
  23. 23.√59 to 1 decimal place? (a) 7.8 (b) 8.0 (c) 7.7 (d) 7.9
  24. 24.√90 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.8
  25. 25.Best estimate of 1527 ÷ 26? (a) 5100 (b) 51 (c) 510
  26. 26.√77 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.6 (d) 8.8
  27. 27.Best estimate of 2112 ÷ 74? (a) 300 (b) 30 (c) 3000
  28. 28.√45 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.7 (d) 7.0
  29. 29.Best estimate of 1608 ÷ 48? (a) 32 (b) 320 (c) 3200
  30. 30.√78 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 9.1 (d) 8.9
  31. 31.Best estimate of 2062 ÷ 53? (a) 4100 (b) 410 (c) 41
  32. 32.Best estimate of 397 ÷ 26? (a) 13 (b) 1300 (c) 130
  33. 33.Best estimate of 1213 ÷ 31? (a) 40 (b) 400 (c) 4000
  34. 34.Best estimate of 2481 ÷ 46? (a) 5000 (b) 500 (c) 50
  35. 35.Best estimate of 2770 ÷ 29? (a) 920 (b) 92 (c) 9200
  36. 36.Best estimate of 2671 ÷ 67? (a) 380 (b) 38 (c) 3800
  37. 37.Best estimate of 7571 ÷ 87? (a) 84 (b) 8400 (c) 840
  38. 38.√75 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 8.8 (d) 8.7
  39. 39.Best estimate of 729 ÷ 28? (a) 240 (b) 24 (c) 2400
  40. 40.Best estimate of 3481 ÷ 88? (a) 39 (b) 390 (c) 3900

Answer key

  1. 68
  2. 85
  3. 75
  4. 28
  5. 13
  6. 7.8
  7. 9.3
  8. 9.1
  9. 9.9
  10. 6.8
  11. 43
  12. 7.6
  13. 31
  14. 12
  15. 29
  16. 8.5
  17. 60
  18. 65
  19. 70
  20. 75
  21. 31
  22. 75
  23. 7.7
  24. 9.5
  25. 51
  26. 8.8
  27. 30
  28. 6.7
  29. 32
  30. 8.8
  31. 41
  32. 13
  33. 40
  34. 50
  35. 92
  36. 38
  37. 84
  38. 8.7
  39. 24
  40. 39

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