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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 806 · 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.√85 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.4
  2. 2.Best estimate of 2272 ÷ 33? (a) 76 (b) 7600 (c) 760
  3. 3.Best estimate of 2183 ÷ 52? (a) 440 (b) 4400 (c) 44
  4. 4.Best estimate of 4358 ÷ 48? (a) 87 (b) 870 (c) 8700
  5. 5.√96 to 1 decimal place? (a) 9.9 (b) 9.6 (c) 9.7 (d) 9.8
  6. 6.Best estimate of 3297 ÷ 57? (a) 550 (b) 5500 (c) 55
  7. 7.Best estimate of 1016 ÷ 24? (a) 510 (b) 51 (c) 5100
  8. 8.Best estimate of 1842 ÷ 52? (a) 370 (b) 3700 (c) 37
  9. 9.Best estimate of 2428 ÷ 76? (a) 300 (b) 3000 (c) 30
  10. 10.Best estimate of 1502 ÷ 68? (a) 210 (b) 2100 (c) 21
  11. 11.√63 to 1 decimal place? (a) 8.0 (b) 7.7 (c) 7.8 (d) 7.9
  12. 12.√50 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 7.2 (d) 6.9
  13. 13.Best estimate of 3544 ÷ 42? (a) 890 (b) 89 (c) 8900
  14. 14.√43 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.9 (d) 6.6
  15. 15.√42 to 1 decimal place? (a) 6.4 (b) 6.5 (c) 6.7 (d) 6.6
  16. 16.Best estimate of 1284 ÷ 58? (a) 210 (b) 21 (c) 2100
  17. 17.Best estimate of 2568 ÷ 53? (a) 51 (b) 5100 (c) 510
  18. 18.√88 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.4
  19. 19.√65 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.0
  20. 20.Best estimate of 1516 ÷ 63? (a) 25 (b) 250 (c) 2500
  21. 21.√71 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.4 (d) 8.6
  22. 22.Best estimate of 2122 ÷ 61? (a) 35 (b) 350 (c) 3500
  23. 23.√92 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.6 (d) 9.5
  24. 24.Best estimate of 3299 ÷ 36? (a) 82 (b) 820 (c) 8200
  25. 25.√61 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 8.0 (d) 7.8
  26. 26.Best estimate of 6111 ÷ 71? (a) 870 (b) 8700 (c) 87
  27. 27.Best estimate of 1782 ÷ 26? (a) 590 (b) 59 (c) 5900
  28. 28.Best estimate of 2263 ÷ 27? (a) 750 (b) 7500 (c) 75
  29. 29.√82 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 9.2
  30. 30.Best estimate of 1145 ÷ 89? (a) 1300 (b) 13 (c) 130
  31. 31.Best estimate of 779 ÷ 24? (a) 39 (b) 390 (c) 3900
  32. 32.Best estimate of 5372 ÷ 79? (a) 6700 (b) 67 (c) 670
  33. 33.Best estimate of 2727 ÷ 63? (a) 4500 (b) 450 (c) 45
  34. 34.Best estimate of 3921 ÷ 49? (a) 780 (b) 7800 (c) 78
  35. 35.Best estimate of 1810 ÷ 58? (a) 3000 (b) 300 (c) 30
  36. 36.√52 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 6.9
  37. 37.√79 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 8.9
  38. 38.√74 to 1 decimal place? (a) 8.8 (b) 8.5 (c) 8.7 (d) 8.6
  39. 39.Best estimate of 1151 ÷ 33? (a) 380 (b) 3800 (c) 38
  40. 40.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.6 (d) 6.5

Answer key

  1. 9.2
  2. 76
  3. 44
  4. 87
  5. 9.8
  6. 55
  7. 51
  8. 37
  9. 30
  10. 21
  11. 7.9
  12. 7.1
  13. 89
  14. 6.6
  15. 6.5
  16. 21
  17. 51
  18. 9.4
  19. 8.1
  20. 25
  21. 8.4
  22. 35
  23. 9.6
  24. 82
  25. 7.8
  26. 87
  27. 59
  28. 75
  29. 9.1
  30. 13
  31. 39
  32. 67
  33. 45
  34. 78
  35. 30
  36. 7.2
  37. 8.9
  38. 8.6
  39. 38
  40. 6.3

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