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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 501 · 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 4277 ÷ 51? (a) 8600 (b) 86 (c) 860
  2. 2.√40 to 1 decimal place? (a) 6.2 (b) 6.4 (c) 6.1 (d) 6.3
  3. 3.√21 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.7 (d) 4.8
  4. 4.Best estimate of 1334 ÷ 43? (a) 330 (b) 3300 (c) 33
  5. 5.Best estimate of 3579 ÷ 76? (a) 45 (b) 450 (c) 4500
  6. 6.√38 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.0 (d) 6.3
  7. 7.Best estimate of 2931 ÷ 57? (a) 4900 (b) 49 (c) 490
  8. 8.√94 to 1 decimal place? (a) 10.0 (b) 9.7 (c) 9.9 (d) 9.8
  9. 9.√43 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.7 (d) 6.6
  10. 10.√85 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.0 (d) 9.2
  11. 11.√92 to 1 decimal place? (a) 9.9 (b) 9.6 (c) 9.8 (d) 9.7
  12. 12.Best estimate of 2019 ÷ 23? (a) 10100 (b) 1010 (c) 101
  13. 13.√20 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.7 (d) 4.4
  14. 14.√44 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.5 (d) 6.7
  15. 15.Best estimate of 1142 ÷ 71? (a) 1600 (b) 160 (c) 16
  16. 16.Best estimate of 1015 ÷ 34? (a) 340 (b) 3400 (c) 34
  17. 17.Best estimate of 3065 ÷ 39? (a) 7700 (b) 770 (c) 77
  18. 18.√78 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.6 (d) 8.8
  19. 19.Best estimate of 501 ÷ 32? (a) 170 (b) 1700 (c) 17
  20. 20.Best estimate of 3938 ÷ 64? (a) 6600 (b) 660 (c) 66
  21. 21.Best estimate of 818 ÷ 53? (a) 1600 (b) 16 (c) 160
  22. 22.Best estimate of 3867 ÷ 78? (a) 4800 (b) 48 (c) 480
  23. 23.Best estimate of 2812 ÷ 67? (a) 4000 (b) 400 (c) 40
  24. 24.√34 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 6.0 (d) 5.9
  25. 25.Best estimate of 4444 ÷ 83? (a) 56 (b) 560 (c) 5600
  26. 26.Best estimate of 815 ÷ 62? (a) 14 (b) 140 (c) 1400
  27. 27.√98 to 1 decimal place? (a) 9.9 (b) 10.0 (c) 10.1 (d) 9.8
  28. 28.√89 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.7 (d) 9.5
  29. 29.√83 to 1 decimal place? (a) 9.4 (b) 9.1 (c) 9.2 (d) 9.3
  30. 30.Best estimate of 2601 ÷ 32? (a) 870 (b) 8700 (c) 87
  31. 31.Best estimate of 6988 ÷ 86? (a) 7800 (b) 780 (c) 78
  32. 32.Best estimate of 1769 ÷ 63? (a) 2900 (b) 290 (c) 29
  33. 33.√22 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.8 (d) 4.6
  34. 34.Best estimate of 1582 ÷ 28? (a) 53 (b) 5300 (c) 530
  35. 35.√46 to 1 decimal place? (a) 6.9 (b) 6.6 (c) 6.7 (d) 6.8
  36. 36.√37 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.1 (d) 5.9
  37. 37.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.3 (d) 5.0
  38. 38.Best estimate of 3696 ÷ 73? (a) 530 (b) 5300 (c) 53
  39. 39.√69 to 1 decimal place? (a) 8.3 (b) 8.0 (c) 8.2 (d) 8.1
  40. 40.Best estimate of 5493 ÷ 69? (a) 78 (b) 780 (c) 7800

Answer key

  1. 86
  2. 6.3
  3. 4.6
  4. 33
  5. 45
  6. 6.2
  7. 49
  8. 9.7
  9. 6.6
  10. 9.2
  11. 9.6
  12. 101
  13. 4.5
  14. 6.6
  15. 16
  16. 34
  17. 77
  18. 8.8
  19. 17
  20. 66
  21. 16
  22. 48
  23. 40
  24. 5.8
  25. 56
  26. 14
  27. 9.9
  28. 9.4
  29. 9.1
  30. 87
  31. 78
  32. 29
  33. 4.7
  34. 53
  35. 6.8
  36. 6.1
  37. 5.1
  38. 53
  39. 8.3
  40. 78

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