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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 839 · 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 1551 ÷ 31? (a) 520 (b) 5200 (c) 52
  2. 2.Best estimate of 1478 ÷ 34? (a) 4900 (b) 49 (c) 490
  3. 3.Best estimate of 6309 ÷ 76? (a) 7900 (b) 79 (c) 790
  4. 4.Best estimate of 1386 ÷ 36? (a) 35 (b) 3500 (c) 350
  5. 5.√90 to 1 decimal place? (a) 9.5 (b) 9.3 (c) 9.4 (d) 9.6
  6. 6.Best estimate of 4607 ÷ 73? (a) 6600 (b) 660 (c) 66
  7. 7.Best estimate of 1850 ÷ 26? (a) 62 (b) 6200 (c) 620
  8. 8.√34 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 5.7 (d) 5.9
  9. 9.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 10.0 (d) 10.2
  10. 10.Best estimate of 947 ÷ 23? (a) 470 (b) 4700 (c) 47
  11. 11.√56 to 1 decimal place? (a) 7.4 (b) 7.3 (c) 7.5 (d) 7.2
  12. 12.√58 to 1 decimal place? (a) 7.3 (b) 7.6 (c) 7.4 (d) 7.5
  13. 13.√61 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 8.0 (d) 7.8
  14. 14.√45 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 7.0 (d) 6.8
  15. 15.Best estimate of 3294 ÷ 62? (a) 550 (b) 5500 (c) 55
  16. 16.√69 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.4 (d) 8.2
  17. 17.√38 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.2 (d) 6.3
  18. 18.Best estimate of 3958 ÷ 77? (a) 4900 (b) 49 (c) 490
  19. 19.Best estimate of 6316 ÷ 84? (a) 790 (b) 7900 (c) 79
  20. 20.√83 to 1 decimal place? (a) 9.0 (b) 9.3 (c) 9.1 (d) 9.2
  21. 21.Best estimate of 866 ÷ 48? (a) 170 (b) 17 (c) 1700
  22. 22.√31 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.4 (d) 5.5
  23. 23.√72 to 1 decimal place? (a) 8.4 (b) 8.6 (c) 8.5 (d) 8.3
  24. 24.Best estimate of 638 ÷ 52? (a) 13 (b) 1300 (c) 130
  25. 25.Best estimate of 635 ÷ 32? (a) 2100 (b) 21 (c) 210
  26. 26.Best estimate of 566 ÷ 28? (a) 1900 (b) 190 (c) 19
  27. 27.Best estimate of 871 ÷ 39? (a) 220 (b) 22 (c) 2200
  28. 28.√96 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.7 (d) 10.0
  29. 29.Best estimate of 3130 ÷ 36? (a) 780 (b) 78 (c) 7800
  30. 30.√40 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.0 (d) 6.2
  31. 31.√30 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.4 (d) 5.7
  32. 32.Best estimate of 1593 ÷ 23? (a) 8000 (b) 800 (c) 80
  33. 33.√92 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.5 (d) 9.6
  34. 34.√21 to 1 decimal place? (a) 4.9 (b) 4.6 (c) 4.7 (d) 4.8
  35. 35.Best estimate of 2559 ÷ 32? (a) 85 (b) 850 (c) 8500
  36. 36.Best estimate of 3768 ÷ 42? (a) 940 (b) 9400 (c) 94
  37. 37.Best estimate of 4944 ÷ 82? (a) 620 (b) 6200 (c) 62
  38. 38.Best estimate of 1588 ÷ 54? (a) 320 (b) 3200 (c) 32
  39. 39.√50 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 7.1
  40. 40.Best estimate of 949 ÷ 26? (a) 3200 (b) 32 (c) 320

Answer key

  1. 52
  2. 49
  3. 79
  4. 35
  5. 9.5
  6. 66
  7. 62
  8. 5.8
  9. 9.9
  10. 47
  11. 7.5
  12. 7.6
  13. 7.8
  14. 6.7
  15. 55
  16. 8.3
  17. 6.2
  18. 49
  19. 79
  20. 9.1
  21. 17
  22. 5.6
  23. 8.5
  24. 13
  25. 21
  26. 19
  27. 22
  28. 9.8
  29. 78
  30. 6.3
  31. 5.5
  32. 80
  33. 9.6
  34. 4.6
  35. 85
  36. 94
  37. 62
  38. 32
  39. 7.1
  40. 32

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