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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 175 · 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 3374 ÷ 83? (a) 420 (b) 4200 (c) 42
  2. 2.Best estimate of 547 ÷ 23? (a) 270 (b) 27 (c) 2700
  3. 3.Best estimate of 915 ÷ 36? (a) 230 (b) 23 (c) 2300
  4. 4.Best estimate of 474 ÷ 26? (a) 160 (b) 1600 (c) 16
  5. 5.Best estimate of 1582 ÷ 36? (a) 400 (b) 4000 (c) 40
  6. 6.Best estimate of 3276 ÷ 87? (a) 360 (b) 3600 (c) 36
  7. 7.√55 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.6 (d) 7.4
  8. 8.√74 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.8 (d) 8.6
  9. 9.√65 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.0 (d) 8.3
  10. 10.Best estimate of 932 ÷ 57? (a) 160 (b) 16 (c) 1600
  11. 11.Best estimate of 437 ÷ 32? (a) 150 (b) 15 (c) 1500
  12. 12.√45 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.8 (d) 6.6
  13. 13.√72 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.6 (d) 8.7
  14. 14.Best estimate of 2413 ÷ 32? (a) 8000 (b) 80 (c) 800
  15. 15.√20 to 1 decimal place? (a) 4.6 (b) 4.3 (c) 4.5 (d) 4.4
  16. 16.√94 to 1 decimal place? (a) 9.8 (b) 9.5 (c) 9.7 (d) 9.6
  17. 17.√32 to 1 decimal place? (a) 5.7 (b) 5.8 (c) 5.9 (d) 5.6
  18. 18.Best estimate of 3554 ÷ 89? (a) 390 (b) 3900 (c) 39
  19. 19.Best estimate of 3211 ÷ 72? (a) 460 (b) 4600 (c) 46
  20. 20.√66 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 7.9 (d) 8.0
  21. 21.Best estimate of 5140 ÷ 88? (a) 57 (b) 5700 (c) 570
  22. 22.Best estimate of 1590 ÷ 43? (a) 400 (b) 40 (c) 4000
  23. 23.Best estimate of 772 ÷ 24? (a) 390 (b) 3900 (c) 39
  24. 24.Best estimate of 3897 ÷ 48? (a) 78 (b) 780 (c) 7800
  25. 25.√28 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.3 (d) 5.5
  26. 26.Best estimate of 1509 ÷ 42? (a) 3800 (b) 380 (c) 38
  27. 27.√69 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.3 (d) 8.5
  28. 28.Best estimate of 728 ÷ 23? (a) 36 (b) 3600 (c) 360
  29. 29.√80 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.2 (d) 9.0
  30. 30.Best estimate of 1604 ÷ 56? (a) 270 (b) 2700 (c) 27
  31. 31.√88 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.1 (d) 9.3
  32. 32.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.0 (d) 6.3
  33. 33.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.8 (d) 7.5
  34. 34.√22 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.4 (d) 4.6
  35. 35.√78 to 1 decimal place? (a) 8.7 (b) 9.0 (c) 8.8 (d) 8.9
  36. 36.Best estimate of 2240 ÷ 67? (a) 320 (b) 32 (c) 3200
  37. 37.Best estimate of 1145 ÷ 39? (a) 290 (b) 29 (c) 2900
  38. 38.√76 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.7 (d) 8.5
  39. 39.Best estimate of 2327 ÷ 31? (a) 780 (b) 7800 (c) 78
  40. 40.Best estimate of 3900 ÷ 76? (a) 49 (b) 490 (c) 4900

Answer key

  1. 42
  2. 27
  3. 23
  4. 16
  5. 40
  6. 36
  7. 7.4
  8. 8.6
  9. 8.1
  10. 16
  11. 15
  12. 6.7
  13. 8.5
  14. 80
  15. 4.5
  16. 9.7
  17. 5.7
  18. 39
  19. 46
  20. 8.1
  21. 57
  22. 40
  23. 39
  24. 78
  25. 5.3
  26. 38
  27. 8.3
  28. 36
  29. 8.9
  30. 27
  31. 9.4
  32. 6.1
  33. 7.6
  34. 4.7
  35. 8.8
  36. 32
  37. 29
  38. 8.7
  39. 78
  40. 49

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