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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 343 · 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 3288 ÷ 52? (a) 660 (b) 6600 (c) 66
  2. 2.√94 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  3. 3.√92 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.9 (d) 9.7
  4. 4.√69 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.4
  5. 5.Best estimate of 2331 ÷ 76? (a) 290 (b) 29 (c) 2900
  6. 6.√30 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.7 (d) 5.5
  7. 7.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.4 (d) 7.1
  8. 8.Best estimate of 1836 ÷ 21? (a) 920 (b) 92 (c) 9200
  9. 9.Best estimate of 2750 ÷ 83? (a) 340 (b) 3400 (c) 34
  10. 10.√41 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.5 (d) 6.7
  11. 11.√85 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.1
  12. 12.√72 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.2 (d) 8.4
  13. 13.Best estimate of 1951 ÷ 43? (a) 4900 (b) 49 (c) 490
  14. 14.Best estimate of 2512 ÷ 38? (a) 6300 (b) 630 (c) 63
  15. 15.Best estimate of 2946 ÷ 44? (a) 7400 (b) 74 (c) 740
  16. 16.Best estimate of 6755 ÷ 87? (a) 750 (b) 7500 (c) 75
  17. 17.Best estimate of 2535 ÷ 69? (a) 360 (b) 36 (c) 3600
  18. 18.√82 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.1
  19. 19.Best estimate of 1190 ÷ 74? (a) 1700 (b) 17 (c) 170
  20. 20.√88 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.4
  21. 21.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.1 (d) 10.0
  22. 22.Best estimate of 4168 ÷ 62? (a) 690 (b) 69 (c) 6900
  23. 23.√31 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 5.6 (d) 5.7
  24. 24.Best estimate of 6045 ÷ 86? (a) 6700 (b) 670 (c) 67
  25. 25.Best estimate of 1170 ÷ 21? (a) 590 (b) 59 (c) 5900
  26. 26.√35 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 5.9
  27. 27.Best estimate of 1206 ÷ 66? (a) 1700 (b) 170 (c) 17
  28. 28.Best estimate of 5900 ÷ 73? (a) 84 (b) 840 (c) 8400
  29. 29.Best estimate of 3130 ÷ 63? (a) 5200 (b) 52 (c) 520
  30. 30.Best estimate of 6478 ÷ 73? (a) 930 (b) 93 (c) 9300
  31. 31.√75 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.9 (d) 8.7
  32. 32.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.3 (d) 8.2
  33. 33.√40 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.6 (d) 6.4
  34. 34.Best estimate of 5988 ÷ 89? (a) 6700 (b) 67 (c) 670
  35. 35.Best estimate of 1279 ÷ 47? (a) 260 (b) 26 (c) 2600
  36. 36.√34 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 5.7 (d) 6.0
  37. 37.Best estimate of 1714 ÷ 86? (a) 1900 (b) 190 (c) 19
  38. 38.√70 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.2 (d) 8.3
  39. 39.√80 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 9.2 (d) 9.0
  40. 40.Best estimate of 2074 ÷ 37? (a) 520 (b) 5200 (c) 52

Answer key

  1. 66
  2. 9.7
  3. 9.6
  4. 8.3
  5. 29
  6. 5.5
  7. 7.4
  8. 92
  9. 34
  10. 6.4
  11. 9.2
  12. 8.5
  13. 49
  14. 63
  15. 74
  16. 75
  17. 36
  18. 9.1
  19. 17
  20. 9.4
  21. 9.9
  22. 69
  23. 5.6
  24. 67
  25. 59
  26. 5.9
  27. 17
  28. 84
  29. 52
  30. 93
  31. 8.7
  32. 8.1
  33. 6.3
  34. 67
  35. 26
  36. 5.8
  37. 19
  38. 8.4
  39. 8.9
  40. 52

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