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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 936 · 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 2519 ÷ 54? (a) 50 (b) 500 (c) 5000
  2. 2.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.4
  3. 3.√40 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.4
  4. 4.Best estimate of 4034 ÷ 88? (a) 450 (b) 4500 (c) 45
  5. 5.Best estimate of 604 ÷ 22? (a) 30 (b) 300 (c) 3000
  6. 6.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.4 (d) 7.5
  7. 7.Best estimate of 3350 ÷ 53? (a) 67 (b) 6700 (c) 670
  8. 8.√78 to 1 decimal place? (a) 9.1 (b) 8.8 (c) 9.0 (d) 8.9
  9. 9.√84 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 9.3
  10. 10.Best estimate of 5012 ÷ 78? (a) 63 (b) 630 (c) 6300
  11. 11.√50 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 6.8 (d) 7.0
  12. 12.Best estimate of 2970 ÷ 58? (a) 50 (b) 5000 (c) 500
  13. 13.Best estimate of 5556 ÷ 59? (a) 930 (b) 93 (c) 9300
  14. 14.Best estimate of 1982 ÷ 42? (a) 5000 (b) 50 (c) 500
  15. 15.Best estimate of 2842 ÷ 32? (a) 950 (b) 95 (c) 9500
  16. 16.Best estimate of 3476 ÷ 39? (a) 870 (b) 8700 (c) 87
  17. 17.Best estimate of 1765 ÷ 56? (a) 290 (b) 29 (c) 2900
  18. 18.Best estimate of 4399 ÷ 73? (a) 6300 (b) 630 (c) 63
  19. 19.Best estimate of 7248 ÷ 87? (a) 810 (b) 81 (c) 8100
  20. 20.Best estimate of 5928 ÷ 72? (a) 850 (b) 85 (c) 8500
  21. 21.Best estimate of 1057 ÷ 48? (a) 210 (b) 2100 (c) 21
  22. 22.Best estimate of 305 ÷ 21? (a) 1500 (b) 150 (c) 15
  23. 23.√23 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  24. 24.Best estimate of 3440 ÷ 52? (a) 6900 (b) 690 (c) 69
  25. 25.√27 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.2 (d) 5.4
  26. 26.Best estimate of 1188 ÷ 87? (a) 1300 (b) 13 (c) 130
  27. 27.√21 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.8 (d) 4.5
  28. 28.Best estimate of 1783 ÷ 26? (a) 59 (b) 5900 (c) 590
  29. 29.Best estimate of 4902 ÷ 83? (a) 610 (b) 6100 (c) 61
  30. 30.Best estimate of 2266 ÷ 28? (a) 7600 (b) 760 (c) 76
  31. 31.√72 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.5 (d) 8.7
  32. 32.Best estimate of 4674 ÷ 73? (a) 6700 (b) 67 (c) 670
  33. 33.Best estimate of 2520 ÷ 37? (a) 630 (b) 6300 (c) 63
  34. 34.Best estimate of 2440 ÷ 72? (a) 35 (b) 350 (c) 3500
  35. 35.Best estimate of 998 ÷ 39? (a) 250 (b) 2500 (c) 25
  36. 36.Best estimate of 635 ÷ 47? (a) 1300 (b) 130 (c) 13
  37. 37.√29 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.4 (d) 5.6
  38. 38.Best estimate of 6298 ÷ 67? (a) 90 (b) 9000 (c) 900
  39. 39.√38 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.3 (d) 6.2
  40. 40.√96 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5

Answer key

  1. 50
  2. 9.1
  3. 6.3
  4. 45
  5. 30
  6. 7.6
  7. 67
  8. 8.8
  9. 9.2
  10. 63
  11. 7.1
  12. 50
  13. 93
  14. 50
  15. 95
  16. 87
  17. 29
  18. 63
  19. 81
  20. 85
  21. 21
  22. 15
  23. 4.8
  24. 69
  25. 5.2
  26. 13
  27. 4.6
  28. 59
  29. 61
  30. 76
  31. 8.5
  32. 67
  33. 63
  34. 35
  35. 25
  36. 13
  37. 5.4
  38. 90
  39. 6.2
  40. 9.8

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