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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 191 · 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.√29 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.7 (d) 5.5
  2. 2.Best estimate of 2045 ÷ 38? (a) 5100 (b) 51 (c) 510
  3. 3.Best estimate of 2110 ÷ 44? (a) 530 (b) 53 (c) 5300
  4. 4.√90 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.3 (d) 9.5
  5. 5.√22 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 5.0 (d) 4.7
  6. 6.Best estimate of 1106 ÷ 73? (a) 16 (b) 1600 (c) 160
  7. 7.√98 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.7 (d) 9.9
  8. 8.Best estimate of 2053 ÷ 22? (a) 10300 (b) 103 (c) 1030
  9. 9.Best estimate of 937 ÷ 31? (a) 3100 (b) 310 (c) 31
  10. 10.√44 to 1 decimal place? (a) 6.8 (b) 6.5 (c) 6.6 (d) 6.7
  11. 11.√61 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 7.8 (d) 8.0
  12. 12.Best estimate of 4746 ÷ 76? (a) 5900 (b) 590 (c) 59
  13. 13.Best estimate of 3972 ÷ 59? (a) 66 (b) 660 (c) 6600
  14. 14.√89 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.2 (d) 9.3
  15. 15.Best estimate of 3459 ÷ 42? (a) 8600 (b) 86 (c) 860
  16. 16.Best estimate of 1204 ÷ 54? (a) 240 (b) 2400 (c) 24
  17. 17.Best estimate of 5568 ÷ 76? (a) 700 (b) 7000 (c) 70
  18. 18.Best estimate of 4976 ÷ 68? (a) 7100 (b) 710 (c) 71
  19. 19.Best estimate of 1330 ÷ 76? (a) 1700 (b) 17 (c) 170
  20. 20.√50 to 1 decimal place? (a) 7.1 (b) 7.3 (c) 7.0 (d) 7.2
  21. 21.Best estimate of 2330 ÷ 27? (a) 78 (b) 780 (c) 7800
  22. 22.Best estimate of 1067 ÷ 66? (a) 15 (b) 1500 (c) 150
  23. 23.Best estimate of 2350 ÷ 26? (a) 780 (b) 78 (c) 7800
  24. 24.Best estimate of 937 ÷ 56? (a) 160 (b) 1600 (c) 16
  25. 25.√34 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.8 (d) 5.6
  26. 26.Best estimate of 7727 ÷ 84? (a) 9700 (b) 97 (c) 970
  27. 27.√40 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.3 (d) 6.5
  28. 28.Best estimate of 1607 ÷ 24? (a) 800 (b) 8000 (c) 80
  29. 29.Best estimate of 1734 ÷ 61? (a) 29 (b) 2900 (c) 290
  30. 30.Best estimate of 5341 ÷ 64? (a) 8900 (b) 890 (c) 89
  31. 31.√58 to 1 decimal place? (a) 7.8 (b) 7.6 (c) 7.9 (d) 7.7
  32. 32.Best estimate of 2086 ÷ 23? (a) 104 (b) 1040 (c) 10400
  33. 33.Best estimate of 2918 ÷ 34? (a) 9700 (b) 97 (c) 970
  34. 34.√94 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 10.0
  35. 35.Best estimate of 4238 ÷ 81? (a) 530 (b) 5300 (c) 53
  36. 36.Best estimate of 2463 ÷ 28? (a) 820 (b) 8200 (c) 82
  37. 37.Best estimate of 1470 ÷ 41? (a) 370 (b) 3700 (c) 37
  38. 38.Best estimate of 2098 ÷ 54? (a) 420 (b) 42 (c) 4200
  39. 39.Best estimate of 1766 ÷ 76? (a) 2200 (b) 220 (c) 22
  40. 40.√26 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.0 (d) 5.2

Answer key

  1. 5.4
  2. 51
  3. 53
  4. 9.5
  5. 4.7
  6. 16
  7. 9.9
  8. 103
  9. 31
  10. 6.6
  11. 7.8
  12. 59
  13. 66
  14. 9.4
  15. 86
  16. 24
  17. 70
  18. 71
  19. 17
  20. 7.1
  21. 78
  22. 15
  23. 78
  24. 16
  25. 5.8
  26. 97
  27. 6.3
  28. 80
  29. 29
  30. 89
  31. 7.6
  32. 104
  33. 97
  34. 9.7
  35. 53
  36. 82
  37. 37
  38. 42
  39. 22
  40. 5.1

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