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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 713 · 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 803 ÷ 33? (a) 27 (b) 2700 (c) 270
  2. 2.√53 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.3 (d) 7.5
  3. 3.√85 to 1 decimal place? (a) 9.2 (b) 8.9 (c) 9.0 (d) 9.1
  4. 4.√58 to 1 decimal place? (a) 7.6 (b) 7.8 (c) 7.5 (d) 7.7
  5. 5.√52 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.0 (d) 6.9
  6. 6.√28 to 1 decimal place? (a) 5.2 (b) 5.1 (c) 5.0 (d) 5.3
  7. 7.Best estimate of 2322 ÷ 86? (a) 260 (b) 26 (c) 2600
  8. 8.√34 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.7 (d) 5.5
  9. 9.Best estimate of 1879 ÷ 74? (a) 27 (b) 270 (c) 2700
  10. 10.Best estimate of 4118 ÷ 63? (a) 6900 (b) 690 (c) 69
  11. 11.Best estimate of 5984 ÷ 66? (a) 850 (b) 85 (c) 8500
  12. 12.√89 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.3 (d) 9.4
  13. 13.Best estimate of 1196 ÷ 73? (a) 170 (b) 1700 (c) 17
  14. 14.Best estimate of 3945 ÷ 61? (a) 660 (b) 66 (c) 6600
  15. 15.Best estimate of 1375 ÷ 36? (a) 34 (b) 340 (c) 3400
  16. 16.Best estimate of 3091 ÷ 37? (a) 770 (b) 77 (c) 7700
  17. 17.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.6 (d) 8.5
  18. 18.Best estimate of 2598 ÷ 54? (a) 5200 (b) 520 (c) 52
  19. 19.√92 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.9
  20. 20.Best estimate of 1922 ÷ 26? (a) 640 (b) 64 (c) 6400
  21. 21.√62 to 1 decimal place? (a) 8.2 (b) 8.0 (c) 7.9 (d) 8.1
  22. 22.Best estimate of 3290 ÷ 63? (a) 550 (b) 5500 (c) 55
  23. 23.Best estimate of 1437 ÷ 61? (a) 24 (b) 240 (c) 2400
  24. 24.Best estimate of 1270 ÷ 52? (a) 250 (b) 2500 (c) 25
  25. 25.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.3 (d) 7.5
  26. 26.Best estimate of 1861 ÷ 56? (a) 3100 (b) 31 (c) 310
  27. 27.Best estimate of 7570 ÷ 84? (a) 950 (b) 95 (c) 9500
  28. 28.√26 to 1 decimal place? (a) 4.9 (b) 5.2 (c) 5.1 (d) 5.0
  29. 29.√80 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.7 (d) 8.9
  30. 30.√32 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.4 (d) 5.5
  31. 31.Best estimate of 4496 ÷ 72? (a) 64 (b) 6400 (c) 640
  32. 32.Best estimate of 2639 ÷ 52? (a) 530 (b) 53 (c) 5300
  33. 33.Best estimate of 6280 ÷ 66? (a) 9000 (b) 90 (c) 900
  34. 34.Best estimate of 3389 ÷ 41? (a) 8500 (b) 85 (c) 850
  35. 35.Best estimate of 2418 ÷ 63? (a) 40 (b) 400 (c) 4000
  36. 36.Best estimate of 4307 ÷ 58? (a) 7200 (b) 72 (c) 720
  37. 37.√23 to 1 decimal place? (a) 5.1 (b) 4.8 (c) 5.0 (d) 4.9
  38. 38.Best estimate of 1359 ÷ 57? (a) 23 (b) 230 (c) 2300
  39. 39.Best estimate of 2935 ÷ 73? (a) 4200 (b) 420 (c) 42
  40. 40.√27 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.5 (d) 5.4

Answer key

  1. 27
  2. 7.3
  3. 9.2
  4. 7.6
  5. 7.2
  6. 5.3
  7. 26
  8. 5.8
  9. 27
  10. 69
  11. 85
  12. 9.4
  13. 17
  14. 66
  15. 34
  16. 77
  17. 8.4
  18. 52
  19. 9.6
  20. 64
  21. 7.9
  22. 55
  23. 24
  24. 25
  25. 7.4
  26. 31
  27. 95
  28. 5.1
  29. 8.9
  30. 5.7
  31. 64
  32. 53
  33. 90
  34. 85
  35. 40
  36. 72
  37. 4.8
  38. 23
  39. 42
  40. 5.2

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