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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 886 · 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 2820 ÷ 81? (a) 350 (b) 3500 (c) 35
  2. 2.√28 to 1 decimal place? (a) 5.5 (b) 5.2 (c) 5.4 (d) 5.3
  3. 3.Best estimate of 2710 ÷ 66? (a) 39 (b) 3900 (c) 390
  4. 4.Best estimate of 2444 ÷ 66? (a) 3500 (b) 350 (c) 35
  5. 5.Best estimate of 3182 ÷ 43? (a) 8000 (b) 80 (c) 800
  6. 6.Best estimate of 1494 ÷ 52? (a) 3000 (b) 300 (c) 30
  7. 7.Best estimate of 3447 ÷ 42? (a) 86 (b) 860 (c) 8600
  8. 8.√70 to 1 decimal place? (a) 8.2 (b) 8.5 (c) 8.4 (d) 8.3
  9. 9.√82 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.0 (d) 9.1
  10. 10.√58 to 1 decimal place? (a) 7.7 (b) 7.4 (c) 7.5 (d) 7.6
  11. 11.Best estimate of 1636 ÷ 69? (a) 23 (b) 230 (c) 2300
  12. 12.Best estimate of 4488 ÷ 76? (a) 5600 (b) 560 (c) 56
  13. 13.√96 to 1 decimal place? (a) 10.0 (b) 9.7 (c) 9.8 (d) 9.9
  14. 14.√32 to 1 decimal place? (a) 5.4 (b) 5.7 (c) 5.5 (d) 5.6
  15. 15.Best estimate of 1675 ÷ 62? (a) 28 (b) 280 (c) 2800
  16. 16.√71 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.5 (d) 8.3
  17. 17.√72 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.4 (d) 8.5
  18. 18.Best estimate of 728 ÷ 32? (a) 2400 (b) 240 (c) 24
  19. 19.√87 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.4
  20. 20.Best estimate of 1146 ÷ 43? (a) 2900 (b) 29 (c) 290
  21. 21.Best estimate of 4312 ÷ 59? (a) 720 (b) 7200 (c) 72
  22. 22.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 10.0
  23. 23.Best estimate of 581 ÷ 26? (a) 19 (b) 190 (c) 1900
  24. 24.√27 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.0 (d) 4.9
  25. 25.√26 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.1 (d) 5.3
  26. 26.Best estimate of 1898 ÷ 32? (a) 63 (b) 630 (c) 6300
  27. 27.Best estimate of 1338 ÷ 33? (a) 45 (b) 4500 (c) 450
  28. 28.Best estimate of 2328 ÷ 47? (a) 4700 (b) 47 (c) 470
  29. 29.Best estimate of 4036 ÷ 61? (a) 6700 (b) 670 (c) 67
  30. 30.√40 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.1 (d) 6.4
  31. 31.√31 to 1 decimal place? (a) 5.7 (b) 5.9 (c) 5.8 (d) 5.6
  32. 32.Best estimate of 1193 ÷ 68? (a) 1700 (b) 170 (c) 17
  33. 33.Best estimate of 682 ÷ 34? (a) 2300 (b) 23 (c) 230
  34. 34.√50 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.3 (d) 7.4
  35. 35.Best estimate of 696 ÷ 46? (a) 1400 (b) 140 (c) 14
  36. 36.√85 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 8.9 (d) 9.0
  37. 37.Best estimate of 1062 ÷ 32? (a) 35 (b) 350 (c) 3500
  38. 38.Best estimate of 3369 ÷ 86? (a) 3700 (b) 37 (c) 370
  39. 39.√23 to 1 decimal place? (a) 5.0 (b) 4.7 (c) 4.8 (d) 4.9
  40. 40.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 10.0 (d) 9.8

Answer key

  1. 35
  2. 5.3
  3. 39
  4. 35
  5. 80
  6. 30
  7. 86
  8. 8.4
  9. 9.1
  10. 7.6
  11. 23
  12. 56
  13. 9.8
  14. 5.7
  15. 28
  16. 8.4
  17. 8.5
  18. 24
  19. 9.3
  20. 29
  21. 72
  22. 9.7
  23. 19
  24. 5.2
  25. 5.1
  26. 63
  27. 45
  28. 47
  29. 67
  30. 6.3
  31. 5.6
  32. 17
  33. 23
  34. 7.1
  35. 14
  36. 9.2
  37. 35
  38. 37
  39. 4.8
  40. 9.9

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