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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 620 · 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.√40 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.2 (d) 6.3
  2. 2.Best estimate of 4407 ÷ 56? (a) 730 (b) 73 (c) 7300
  3. 3.Best estimate of 864 ÷ 31? (a) 2900 (b) 290 (c) 29
  4. 4.√58 to 1 decimal place? (a) 7.7 (b) 7.4 (c) 7.5 (d) 7.6
  5. 5.√55 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.7
  6. 6.Best estimate of 4761 ÷ 53? (a) 950 (b) 9500 (c) 95
  7. 7.√20 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.5 (d) 4.8
  8. 8.√82 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.2 (d) 9.3
  9. 9.√92 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.6 (d) 9.3
  10. 10.√98 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.6 (d) 9.9
  11. 11.Best estimate of 1924 ÷ 37? (a) 48 (b) 4800 (c) 480
  12. 12.Best estimate of 2869 ÷ 77? (a) 360 (b) 3600 (c) 36
  13. 13.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.9
  14. 14.√44 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.7
  15. 15.Best estimate of 2145 ÷ 42? (a) 540 (b) 5400 (c) 54
  16. 16.Best estimate of 2867 ÷ 41? (a) 7200 (b) 720 (c) 72
  17. 17.Best estimate of 1690 ÷ 26? (a) 5600 (b) 560 (c) 56
  18. 18.Best estimate of 825 ÷ 32? (a) 2800 (b) 280 (c) 28
  19. 19.Best estimate of 4171 ÷ 68? (a) 6000 (b) 60 (c) 600
  20. 20.Best estimate of 1094 ÷ 27? (a) 36 (b) 3600 (c) 360
  21. 21.√69 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.3 (d) 8.6
  22. 22.Best estimate of 2415 ÷ 27? (a) 8100 (b) 810 (c) 81
  23. 23.Best estimate of 1075 ÷ 54? (a) 2200 (b) 220 (c) 22
  24. 24.Best estimate of 1316 ÷ 48? (a) 260 (b) 2600 (c) 26
  25. 25.Best estimate of 1761 ÷ 24? (a) 880 (b) 88 (c) 8800
  26. 26.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.1 (d) 4.8
  27. 27.√89 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.5 (d) 9.4
  28. 28.Best estimate of 1118 ÷ 36? (a) 28 (b) 2800 (c) 280
  29. 29.Best estimate of 4476 ÷ 48? (a) 9000 (b) 900 (c) 90
  30. 30.√66 to 1 decimal place? (a) 8.4 (b) 8.1 (c) 8.3 (d) 8.2
  31. 31.Best estimate of 1692 ÷ 46? (a) 340 (b) 3400 (c) 34
  32. 32.Best estimate of 4963 ÷ 69? (a) 710 (b) 71 (c) 7100
  33. 33.Best estimate of 1231 ÷ 51? (a) 2500 (b) 25 (c) 250
  34. 34.√70 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.2
  35. 35.Best estimate of 2960 ÷ 82? (a) 37 (b) 370 (c) 3700
  36. 36.Best estimate of 3899 ÷ 83? (a) 49 (b) 490 (c) 4900
  37. 37.Best estimate of 1156 ÷ 86? (a) 130 (b) 13 (c) 1300
  38. 38.√61 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.9
  39. 39.Best estimate of 2313 ÷ 27? (a) 7700 (b) 77 (c) 770
  40. 40.Best estimate of 1046 ÷ 26? (a) 3500 (b) 350 (c) 35

Answer key

  1. 6.3
  2. 73
  3. 29
  4. 7.6
  5. 7.4
  6. 95
  7. 4.5
  8. 9.1
  9. 9.6
  10. 9.9
  11. 48
  12. 36
  13. 5.8
  14. 6.6
  15. 54
  16. 72
  17. 56
  18. 28
  19. 60
  20. 36
  21. 8.3
  22. 81
  23. 22
  24. 26
  25. 88
  26. 5.1
  27. 9.4
  28. 28
  29. 90
  30. 8.1
  31. 34
  32. 71
  33. 25
  34. 8.4
  35. 37
  36. 49
  37. 13
  38. 7.8
  39. 77
  40. 35

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