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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 64 · 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) 6.7 (b) 6.9 (c) 6.8 (d) 7.0
  2. 2.Best estimate of 1791 ÷ 36? (a) 450 (b) 4500 (c) 45
  3. 3.Best estimate of 741 ÷ 32? (a) 250 (b) 25 (c) 2500
  4. 4.Best estimate of 4266 ÷ 71? (a) 6100 (b) 61 (c) 610
  5. 5.Best estimate of 2018 ÷ 53? (a) 4000 (b) 40 (c) 400
  6. 6.Best estimate of 1195 ÷ 29? (a) 4000 (b) 40 (c) 400
  7. 7.√59 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.7 (d) 7.8
  8. 8.Best estimate of 2972 ÷ 83? (a) 3700 (b) 370 (c) 37
  9. 9.√29 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.4 (d) 5.1
  10. 10.√90 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.8
  11. 11.Best estimate of 3140 ÷ 79? (a) 39 (b) 3900 (c) 390
  12. 12.Best estimate of 4808 ÷ 54? (a) 960 (b) 9600 (c) 96
  13. 13.√56 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.3 (d) 7.6
  14. 14.Best estimate of 6449 ÷ 72? (a) 920 (b) 9200 (c) 92
  15. 15.Best estimate of 1535 ÷ 74? (a) 220 (b) 2200 (c) 22
  16. 16.Best estimate of 925 ÷ 28? (a) 3100 (b) 31 (c) 310
  17. 17.Best estimate of 2025 ÷ 53? (a) 41 (b) 4100 (c) 410
  18. 18.√66 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 7.9
  19. 19.Best estimate of 1288 ÷ 44? (a) 320 (b) 3200 (c) 32
  20. 20.√32 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.6 (d) 5.7
  21. 21.Best estimate of 534 ÷ 42? (a) 13 (b) 130 (c) 1300
  22. 22.Best estimate of 966 ÷ 37? (a) 2400 (b) 240 (c) 24
  23. 23.Best estimate of 783 ÷ 58? (a) 1300 (b) 130 (c) 13
  24. 24.Best estimate of 938 ÷ 59? (a) 1600 (b) 160 (c) 16
  25. 25.√22 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.6 (d) 4.4
  26. 26.Best estimate of 3886 ÷ 89? (a) 43 (b) 4300 (c) 430
  27. 27.Best estimate of 3563 ÷ 69? (a) 5100 (b) 51 (c) 510
  28. 28.√76 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.4 (d) 8.7
  29. 29.Best estimate of 1580 ÷ 47? (a) 32 (b) 3200 (c) 320
  30. 30.Best estimate of 842 ÷ 28? (a) 2800 (b) 280 (c) 28
  31. 31.Best estimate of 3003 ÷ 46? (a) 600 (b) 6000 (c) 60
  32. 32.√86 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.4
  33. 33.Best estimate of 773 ÷ 32? (a) 26 (b) 2600 (c) 260
  34. 34.Best estimate of 1349 ÷ 24? (a) 670 (b) 6700 (c) 67
  35. 35.√31 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.4 (d) 5.5
  36. 36.√71 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.5 (d) 8.2
  37. 37.√53 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.4 (d) 7.3
  38. 38.Best estimate of 1218 ÷ 58? (a) 200 (b) 2000 (c) 20
  39. 39.√92 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.7 (d) 9.6
  40. 40.Best estimate of 4554 ÷ 86? (a) 5100 (b) 51 (c) 510

Answer key

  1. 6.9
  2. 45
  3. 25
  4. 61
  5. 40
  6. 40
  7. 7.7
  8. 37
  9. 5.4
  10. 9.5
  11. 39
  12. 96
  13. 7.5
  14. 92
  15. 22
  16. 31
  17. 41
  18. 8.1
  19. 32
  20. 5.7
  21. 13
  22. 24
  23. 13
  24. 16
  25. 4.7
  26. 43
  27. 51
  28. 8.7
  29. 32
  30. 28
  31. 60
  32. 9.3
  33. 26
  34. 67
  35. 5.6
  36. 8.4
  37. 7.3
  38. 20
  39. 9.6
  40. 51

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