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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 779 · 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.√86 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.4 (d) 9.5
  2. 2.√94 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  3. 3.√30 to 1 decimal place? (a) 5.5 (b) 5.3 (c) 5.4 (d) 5.6
  4. 4.Best estimate of 2517 ÷ 39? (a) 630 (b) 6300 (c) 63
  5. 5.√56 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.5 (d) 7.6
  6. 6.Best estimate of 4056 ÷ 56? (a) 6800 (b) 680 (c) 68
  7. 7.Best estimate of 5114 ÷ 59? (a) 850 (b) 8500 (c) 85
  8. 8.√80 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.9 (d) 8.8
  9. 9.√75 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 9.0
  10. 10.√38 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.1
  11. 11.Best estimate of 5434 ÷ 82? (a) 680 (b) 68 (c) 6800
  12. 12.Best estimate of 2208 ÷ 29? (a) 74 (b) 740 (c) 7400
  13. 13.√24 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.9 (d) 5.0
  14. 14.√35 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 5.8 (d) 5.9
  15. 15.Best estimate of 2802 ÷ 88? (a) 31 (b) 310 (c) 3100
  16. 16.√55 to 1 decimal place? (a) 7.5 (b) 7.7 (c) 7.6 (d) 7.4
  17. 17.Best estimate of 1399 ÷ 48? (a) 2800 (b) 28 (c) 280
  18. 18.√69 to 1 decimal place? (a) 8.6 (b) 8.3 (c) 8.5 (d) 8.4
  19. 19.Best estimate of 4108 ÷ 52? (a) 8200 (b) 820 (c) 82
  20. 20.Best estimate of 642 ÷ 49? (a) 130 (b) 13 (c) 1300
  21. 21.√82 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 9.1 (d) 8.9
  22. 22.Best estimate of 2265 ÷ 74? (a) 3200 (b) 320 (c) 32
  23. 23.Best estimate of 7511 ÷ 89? (a) 830 (b) 83 (c) 8300
  24. 24.Best estimate of 1191 ÷ 51? (a) 2400 (b) 240 (c) 24
  25. 25.√72 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.5
  26. 26.Best estimate of 4610 ÷ 56? (a) 77 (b) 770 (c) 7700
  27. 27.Best estimate of 2827 ÷ 41? (a) 7100 (b) 710 (c) 71
  28. 28.√22 to 1 decimal place? (a) 4.5 (b) 4.8 (c) 4.6 (d) 4.7
  29. 29.Best estimate of 2826 ÷ 51? (a) 570 (b) 5700 (c) 57
  30. 30.Best estimate of 2252 ÷ 36? (a) 560 (b) 56 (c) 5600
  31. 31.Best estimate of 1546 ÷ 59? (a) 2600 (b) 26 (c) 260
  32. 32.Best estimate of 906 ÷ 31? (a) 30 (b) 300 (c) 3000
  33. 33.√50 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.0
  34. 34.√26 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.0
  35. 35.√79 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 8.9 (d) 9.0
  36. 36.Best estimate of 1995 ÷ 21? (a) 1000 (b) 10000 (c) 100
  37. 37.√88 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.7 (d) 9.5
  38. 38.Best estimate of 2561 ÷ 64? (a) 4300 (b) 43 (c) 430
  39. 39.Best estimate of 2192 ÷ 39? (a) 550 (b) 55 (c) 5500
  40. 40.Best estimate of 2817 ÷ 32? (a) 940 (b) 94 (c) 9400

Answer key

  1. 9.3
  2. 9.7
  3. 5.5
  4. 63
  5. 7.5
  6. 68
  7. 85
  8. 8.9
  9. 8.7
  10. 6.2
  11. 68
  12. 74
  13. 4.9
  14. 5.9
  15. 31
  16. 7.4
  17. 28
  18. 8.3
  19. 82
  20. 13
  21. 9.1
  22. 32
  23. 83
  24. 24
  25. 8.5
  26. 77
  27. 71
  28. 4.7
  29. 57
  30. 56
  31. 26
  32. 30
  33. 7.1
  34. 5.1
  35. 8.9
  36. 100
  37. 9.4
  38. 43
  39. 55
  40. 94

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