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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 394 · 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.√50 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.4
  2. 2.Best estimate of 1688 ÷ 52? (a) 34 (b) 340 (c) 3400
  3. 3.√35 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 5.8 (d) 6.1
  4. 4.√56 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.5 (d) 7.6
  5. 5.√63 to 1 decimal place? (a) 8.2 (b) 8.0 (c) 8.1 (d) 7.9
  6. 6.√53 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.5 (d) 7.3
  7. 7.Best estimate of 1754 ÷ 62? (a) 29 (b) 290 (c) 2900
  8. 8.Best estimate of 3044 ÷ 44? (a) 760 (b) 76 (c) 7600
  9. 9.Best estimate of 2035 ÷ 69? (a) 2900 (b) 290 (c) 29
  10. 10.Best estimate of 4074 ÷ 46? (a) 810 (b) 81 (c) 8100
  11. 11.Best estimate of 3510 ÷ 46? (a) 700 (b) 70 (c) 7000
  12. 12.√20 to 1 decimal place? (a) 4.2 (b) 4.3 (c) 4.4 (d) 4.5
  13. 13.Best estimate of 3557 ÷ 47? (a) 710 (b) 7100 (c) 71
  14. 14.Best estimate of 1664 ÷ 33? (a) 5500 (b) 550 (c) 55
  15. 15.√65 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 8.2
  16. 16.Best estimate of 1293 ÷ 26? (a) 4300 (b) 430 (c) 43
  17. 17.√71 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.4 (d) 8.7
  18. 18.√40 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.5 (d) 6.6
  19. 19.√24 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.2 (d) 5.0
  20. 20.√96 to 1 decimal place? (a) 9.9 (b) 10.0 (c) 10.1 (d) 9.8
  21. 21.Best estimate of 3311 ÷ 69? (a) 47 (b) 4700 (c) 470
  22. 22.Best estimate of 772 ÷ 63? (a) 1300 (b) 130 (c) 13
  23. 23.√74 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.7
  24. 24.√37 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.3 (d) 6.2
  25. 25.√47 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 7.1
  26. 26.√32 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  27. 27.Best estimate of 1851 ÷ 83? (a) 2300 (b) 23 (c) 230
  28. 28.Best estimate of 2880 ÷ 72? (a) 410 (b) 4100 (c) 41
  29. 29.Best estimate of 6372 ÷ 74? (a) 9100 (b) 910 (c) 91
  30. 30.√77 to 1 decimal place? (a) 8.7 (b) 9.0 (c) 8.9 (d) 8.8
  31. 31.Best estimate of 2108 ÷ 29? (a) 700 (b) 7000 (c) 70
  32. 32.Best estimate of 1410 ÷ 42? (a) 3500 (b) 350 (c) 35
  33. 33.Best estimate of 2262 ÷ 87? (a) 2500 (b) 250 (c) 25
  34. 34.Best estimate of 2663 ÷ 36? (a) 670 (b) 6700 (c) 67
  35. 35.Best estimate of 1775 ÷ 82? (a) 220 (b) 2200 (c) 22
  36. 36.Best estimate of 1038 ÷ 76? (a) 13 (b) 1300 (c) 130
  37. 37.Best estimate of 3849 ÷ 48? (a) 7700 (b) 77 (c) 770
  38. 38.Best estimate of 3088 ÷ 41? (a) 77 (b) 770 (c) 7700
  39. 39.Best estimate of 1239 ÷ 21? (a) 620 (b) 62 (c) 6200
  40. 40.Best estimate of 6592 ÷ 73? (a) 940 (b) 9400 (c) 94

Answer key

  1. 7.1
  2. 34
  3. 5.9
  4. 7.5
  5. 7.9
  6. 7.3
  7. 29
  8. 76
  9. 29
  10. 81
  11. 70
  12. 4.5
  13. 71
  14. 55
  15. 8.1
  16. 43
  17. 8.4
  18. 6.3
  19. 4.9
  20. 9.8
  21. 47
  22. 13
  23. 8.6
  24. 6.1
  25. 6.9
  26. 5.7
  27. 23
  28. 41
  29. 91
  30. 8.8
  31. 70
  32. 35
  33. 25
  34. 67
  35. 22
  36. 13
  37. 77
  38. 77
  39. 62
  40. 94

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