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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 933 · 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.√94 to 1 decimal place? (a) 9.7 (b) 10.0 (c) 9.9 (d) 9.8
  2. 2.√30 to 1 decimal place? (a) 5.3 (b) 5.6 (c) 5.5 (d) 5.4
  3. 3.Best estimate of 3985 ÷ 46? (a) 80 (b) 8000 (c) 800
  4. 4.Best estimate of 4030 ÷ 68? (a) 580 (b) 5800 (c) 58
  5. 5.√67 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.1
  6. 6.Best estimate of 3781 ÷ 41? (a) 950 (b) 9500 (c) 95
  7. 7.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 5.2 (d) 4.9
  8. 8.√98 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 10.0 (d) 9.8
  9. 9.Best estimate of 1726 ÷ 46? (a) 350 (b) 35 (c) 3500
  10. 10.Best estimate of 1030 ÷ 47? (a) 2100 (b) 210 (c) 21
  11. 11.Best estimate of 2580 ÷ 46? (a) 52 (b) 520 (c) 5200
  12. 12.Best estimate of 752 ÷ 34? (a) 2500 (b) 250 (c) 25
  13. 13.Best estimate of 659 ÷ 26? (a) 220 (b) 22 (c) 2200
  14. 14.Best estimate of 4211 ÷ 74? (a) 600 (b) 60 (c) 6000
  15. 15.Best estimate of 1309 ÷ 36? (a) 33 (b) 3300 (c) 330
  16. 16.Best estimate of 4760 ÷ 69? (a) 6800 (b) 680 (c) 68
  17. 17.Best estimate of 5785 ÷ 72? (a) 830 (b) 83 (c) 8300
  18. 18.Best estimate of 1055 ÷ 56? (a) 180 (b) 1800 (c) 18
  19. 19.√62 to 1 decimal place? (a) 7.7 (b) 7.9 (c) 7.6 (d) 7.8
  20. 20.√38 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.5 (d) 6.2
  21. 21.Best estimate of 6858 ÷ 72? (a) 980 (b) 98 (c) 9800
  22. 22.Best estimate of 1773 ÷ 56? (a) 300 (b) 3000 (c) 30
  23. 23.√96 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.8 (d) 9.6
  24. 24.√92 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.4 (d) 9.5
  25. 25.√24 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  26. 26.Best estimate of 1582 ÷ 62? (a) 260 (b) 2600 (c) 26
  27. 27.√44 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.7 (d) 6.9
  28. 28.√21 to 1 decimal place? (a) 4.3 (b) 4.5 (c) 4.6 (d) 4.4
  29. 29.Best estimate of 3270 ÷ 48? (a) 6500 (b) 65 (c) 650
  30. 30.Best estimate of 1666 ÷ 28? (a) 56 (b) 560 (c) 5600
  31. 31.Best estimate of 1383 ÷ 52? (a) 2800 (b) 280 (c) 28
  32. 32.Best estimate of 3035 ÷ 47? (a) 610 (b) 6100 (c) 61
  33. 33.Best estimate of 3339 ÷ 53? (a) 670 (b) 6700 (c) 67
  34. 34.√58 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.7 (d) 7.4
  35. 35.Best estimate of 1816 ÷ 28? (a) 61 (b) 6100 (c) 610
  36. 36.Best estimate of 7756 ÷ 83? (a) 9700 (b) 97 (c) 970
  37. 37.√80 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 9.2 (d) 9.0
  38. 38.√40 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.2 (d) 6.3
  39. 39.Best estimate of 4953 ÷ 52? (a) 99 (b) 9900 (c) 990
  40. 40.Best estimate of 5968 ÷ 79? (a) 7500 (b) 75 (c) 750

Answer key

  1. 9.7
  2. 5.5
  3. 80
  4. 58
  5. 8.2
  6. 95
  7. 5.1
  8. 9.9
  9. 35
  10. 21
  11. 52
  12. 25
  13. 22
  14. 60
  15. 33
  16. 68
  17. 83
  18. 18
  19. 7.9
  20. 6.2
  21. 98
  22. 30
  23. 9.8
  24. 9.6
  25. 4.9
  26. 26
  27. 6.6
  28. 4.6
  29. 65
  30. 56
  31. 28
  32. 61
  33. 67
  34. 7.6
  35. 61
  36. 97
  37. 8.9
  38. 6.3
  39. 99
  40. 75

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