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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 973 · 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 7097 ÷ 88? (a) 79 (b) 7900 (c) 790
  2. 2.Best estimate of 511 ÷ 42? (a) 130 (b) 13 (c) 1300
  3. 3.√65 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 8.0 (d) 7.8
  4. 4.Best estimate of 2687 ÷ 56? (a) 45 (b) 450 (c) 4500
  5. 5.√40 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.3 (d) 6.4
  6. 6.√94 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.4 (d) 9.7
  7. 7.√78 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.8 (d) 8.9
  8. 8.Best estimate of 2827 ÷ 32? (a) 9400 (b) 94 (c) 940
  9. 9.√41 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.5 (d) 6.4
  10. 10.√67 to 1 decimal place? (a) 8.4 (b) 8.2 (c) 8.1 (d) 8.3
  11. 11.√52 to 1 decimal place? (a) 7.0 (b) 7.3 (c) 7.2 (d) 7.1
  12. 12.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 9.7
  13. 13.Best estimate of 2748 ÷ 43? (a) 6900 (b) 69 (c) 690
  14. 14.Best estimate of 4997 ÷ 66? (a) 7100 (b) 71 (c) 710
  15. 15.√47 to 1 decimal place? (a) 6.9 (b) 6.6 (c) 6.8 (d) 6.7
  16. 16.√48 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.6 (d) 6.7
  17. 17.Best estimate of 4244 ÷ 52? (a) 850 (b) 8500 (c) 85
  18. 18.√72 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.4 (d) 8.2
  19. 19.√61 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.8 (d) 7.5
  20. 20.√30 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.7 (d) 5.5
  21. 21.√50 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.9 (d) 6.8
  22. 22.Best estimate of 1736 ÷ 41? (a) 430 (b) 43 (c) 4300
  23. 23.√85 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 8.9 (d) 9.0
  24. 24.Best estimate of 414 ÷ 28? (a) 140 (b) 1400 (c) 14
  25. 25.Best estimate of 4600 ÷ 54? (a) 920 (b) 9200 (c) 92
  26. 26.√34 to 1 decimal place? (a) 6.1 (b) 5.8 (c) 6.0 (d) 5.9
  27. 27.Best estimate of 2265 ÷ 73? (a) 3200 (b) 320 (c) 32
  28. 28.Best estimate of 1514 ÷ 36? (a) 38 (b) 3800 (c) 380
  29. 29.Best estimate of 4680 ÷ 56? (a) 78 (b) 780 (c) 7800
  30. 30.Best estimate of 953 ÷ 51? (a) 190 (b) 1900 (c) 19
  31. 31.Best estimate of 1781 ÷ 42? (a) 450 (b) 4500 (c) 45
  32. 32.Best estimate of 1098 ÷ 38? (a) 27 (b) 2700 (c) 270
  33. 33.Best estimate of 5035 ÷ 82? (a) 63 (b) 630 (c) 6300
  34. 34.Best estimate of 4940 ÷ 66? (a) 71 (b) 7100 (c) 710
  35. 35.Best estimate of 1042 ÷ 59? (a) 17 (b) 1700 (c) 170
  36. 36.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.6
  37. 37.Best estimate of 2935 ÷ 74? (a) 420 (b) 4200 (c) 42
  38. 38.√74 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.9
  39. 39.√32 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.8 (d) 6.0
  40. 40.Best estimate of 2701 ÷ 71? (a) 390 (b) 3900 (c) 39

Answer key

  1. 79
  2. 13
  3. 8.1
  4. 45
  5. 6.3
  6. 9.7
  7. 8.8
  8. 94
  9. 6.4
  10. 8.2
  11. 7.2
  12. 9.9
  13. 69
  14. 71
  15. 6.9
  16. 6.9
  17. 85
  18. 8.5
  19. 7.8
  20. 5.5
  21. 7.1
  22. 43
  23. 9.2
  24. 14
  25. 92
  26. 5.8
  27. 32
  28. 38
  29. 78
  30. 19
  31. 45
  32. 27
  33. 63
  34. 71
  35. 17
  36. 8.3
  37. 42
  38. 8.6
  39. 5.7
  40. 39

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