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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 879 · 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 1281 ÷ 76? (a) 16 (b) 1600 (c) 160
  2. 2.Best estimate of 2480 ÷ 63? (a) 41 (b) 4100 (c) 410
  3. 3.√23 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.8 (d) 5.1
  4. 4.√94 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.9
  5. 5.Best estimate of 2408 ÷ 36? (a) 600 (b) 6000 (c) 60
  6. 6.Best estimate of 1901 ÷ 73? (a) 27 (b) 270 (c) 2700
  7. 7.√65 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.0
  8. 8.Best estimate of 1279 ÷ 27? (a) 43 (b) 4300 (c) 430
  9. 9.√77 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.8 (d) 8.9
  10. 10.Best estimate of 2340 ÷ 46? (a) 470 (b) 47 (c) 4700
  11. 11.√50 to 1 decimal place? (a) 7.0 (b) 7.2 (c) 7.1 (d) 7.3
  12. 12.√75 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 9.0 (d) 8.8
  13. 13.√61 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 7.7
  14. 14.√82 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.0 (d) 9.2
  15. 15.Best estimate of 1244 ÷ 27? (a) 41 (b) 4100 (c) 410
  16. 16.Best estimate of 3055 ÷ 33? (a) 1020 (b) 102 (c) 10200
  17. 17.√40 to 1 decimal place? (a) 6.3 (b) 6.1 (c) 6.4 (d) 6.2
  18. 18.Best estimate of 1301 ÷ 34? (a) 430 (b) 43 (c) 4300
  19. 19.√26 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 5.1 (d) 4.9
  20. 20.Best estimate of 999 ÷ 29? (a) 3300 (b) 33 (c) 330
  21. 21.√66 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 8.0 (d) 8.2
  22. 22.Best estimate of 2403 ÷ 76? (a) 300 (b) 3000 (c) 30
  23. 23.Best estimate of 2026 ÷ 68? (a) 2900 (b) 290 (c) 29
  24. 24.√31 to 1 decimal place? (a) 5.6 (b) 5.4 (c) 5.5 (d) 5.3
  25. 25.Best estimate of 2980 ÷ 71? (a) 43 (b) 430 (c) 4300
  26. 26.Best estimate of 3238 ÷ 62? (a) 540 (b) 5400 (c) 54
  27. 27.Best estimate of 1233 ÷ 78? (a) 150 (b) 15 (c) 1500
  28. 28.Best estimate of 5651 ÷ 69? (a) 81 (b) 8100 (c) 810
  29. 29.Best estimate of 1627 ÷ 43? (a) 41 (b) 410 (c) 4100
  30. 30.Best estimate of 1188 ÷ 39? (a) 30 (b) 3000 (c) 300
  31. 31.√43 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.5 (d) 6.7
  32. 32.√58 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.8 (d) 7.5
  33. 33.√48 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 6.9 (d) 6.7
  34. 34.√87 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.0 (d) 9.1
  35. 35.Best estimate of 4870 ÷ 73? (a) 7000 (b) 70 (c) 700
  36. 36.Best estimate of 4371 ÷ 68? (a) 6200 (b) 62 (c) 620
  37. 37.√98 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 10.0 (d) 9.9
  38. 38.√55 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.7
  39. 39.Best estimate of 3558 ÷ 64? (a) 590 (b) 5900 (c) 59
  40. 40.Best estimate of 3633 ÷ 44? (a) 9100 (b) 910 (c) 91

Answer key

  1. 16
  2. 41
  3. 4.8
  4. 9.7
  5. 60
  6. 27
  7. 8.1
  8. 43
  9. 8.8
  10. 47
  11. 7.1
  12. 8.7
  13. 7.8
  14. 9.1
  15. 41
  16. 102
  17. 6.3
  18. 43
  19. 5.1
  20. 33
  21. 8.1
  22. 30
  23. 29
  24. 5.6
  25. 43
  26. 54
  27. 15
  28. 81
  29. 41
  30. 30
  31. 6.6
  32. 7.6
  33. 6.9
  34. 9.3
  35. 70
  36. 62
  37. 9.9
  38. 7.4
  39. 59
  40. 91

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