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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 829 · 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 3703 ÷ 48? (a) 7400 (b) 74 (c) 740
  2. 2.√50 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 6.9 (d) 7.1
  3. 3.Best estimate of 4204 ÷ 74? (a) 600 (b) 60 (c) 6000
  4. 4.Best estimate of 4524 ÷ 77? (a) 57 (b) 570 (c) 5700
  5. 5.Best estimate of 1199 ÷ 23? (a) 600 (b) 60 (c) 6000
  6. 6.Best estimate of 2497 ÷ 62? (a) 420 (b) 42 (c) 4200
  7. 7.Best estimate of 1223 ÷ 29? (a) 4100 (b) 41 (c) 410
  8. 8.Best estimate of 1854 ÷ 66? (a) 260 (b) 2600 (c) 26
  9. 9.√30 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.7 (d) 5.4
  10. 10.Best estimate of 2324 ÷ 57? (a) 39 (b) 3900 (c) 390
  11. 11.√55 to 1 decimal place? (a) 7.2 (b) 7.5 (c) 7.3 (d) 7.4
  12. 12.Best estimate of 3131 ÷ 43? (a) 780 (b) 78 (c) 7800
  13. 13.√43 to 1 decimal place? (a) 6.7 (b) 6.8 (c) 6.5 (d) 6.6
  14. 14.√48 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 6.7 (d) 6.9
  15. 15.Best estimate of 4316 ÷ 78? (a) 5400 (b) 54 (c) 540
  16. 16.√71 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.2 (d) 8.3
  17. 17.Best estimate of 2333 ÷ 51? (a) 47 (b) 4700 (c) 470
  18. 18.Best estimate of 1354 ÷ 53? (a) 27 (b) 270 (c) 2700
  19. 19.√34 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.1 (d) 5.8
  20. 20.Best estimate of 3445 ÷ 56? (a) 57 (b) 570 (c) 5700
  21. 21.Best estimate of 693 ÷ 36? (a) 170 (b) 1700 (c) 17
  22. 22.Best estimate of 4657 ÷ 58? (a) 780 (b) 7800 (c) 78
  23. 23.Best estimate of 2765 ÷ 66? (a) 4000 (b) 40 (c) 400
  24. 24.Best estimate of 1992 ÷ 23? (a) 1000 (b) 10000 (c) 100
  25. 25.Best estimate of 1748 ÷ 54? (a) 350 (b) 3500 (c) 35
  26. 26.Best estimate of 1334 ÷ 67? (a) 19 (b) 1900 (c) 190
  27. 27.Best estimate of 1405 ÷ 78? (a) 1800 (b) 180 (c) 18
  28. 28.Best estimate of 2401 ÷ 82? (a) 300 (b) 3000 (c) 30
  29. 29.√74 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.5 (d) 8.7
  30. 30.Best estimate of 1359 ÷ 54? (a) 270 (b) 27 (c) 2700
  31. 31.√84 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.0
  32. 32.Best estimate of 4282 ÷ 89? (a) 48 (b) 480 (c) 4800
  33. 33.√27 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.5 (d) 5.2
  34. 34.Best estimate of 728 ÷ 56? (a) 1200 (b) 12 (c) 120
  35. 35.√51 to 1 decimal place? (a) 7.1 (b) 6.9 (c) 7.2 (d) 7.0
  36. 36.Best estimate of 2820 ÷ 57? (a) 470 (b) 47 (c) 4700
  37. 37.√76 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.8 (d) 8.7
  38. 38.Best estimate of 1399 ÷ 27? (a) 4700 (b) 47 (c) 470
  39. 39.√37 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.3 (d) 6.2
  40. 40.Best estimate of 966 ÷ 63? (a) 160 (b) 16 (c) 1600

Answer key

  1. 74
  2. 7.1
  3. 60
  4. 57
  5. 60
  6. 42
  7. 41
  8. 26
  9. 5.5
  10. 39
  11. 7.4
  12. 78
  13. 6.6
  14. 6.9
  15. 54
  16. 8.4
  17. 47
  18. 27
  19. 5.8
  20. 57
  21. 17
  22. 78
  23. 40
  24. 100
  25. 35
  26. 19
  27. 18
  28. 30
  29. 8.6
  30. 27
  31. 9.2
  32. 48
  33. 5.2
  34. 12
  35. 7.1
  36. 47
  37. 8.7
  38. 47
  39. 6.1
  40. 16

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