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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 369 · 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.√74 to 1 decimal place? (a) 8.7 (b) 8.4 (c) 8.5 (d) 8.6
  2. 2.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.0 (d) 5.9
  3. 3.√78 to 1 decimal place? (a) 8.9 (b) 9.1 (c) 8.8 (d) 9.0
  4. 4.√30 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.7 (d) 5.5
  5. 5.Best estimate of 2418 ÷ 29? (a) 810 (b) 81 (c) 8100
  6. 6.√46 to 1 decimal place? (a) 6.9 (b) 6.7 (c) 6.6 (d) 6.8
  7. 7.√79 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.1 (d) 9.0
  8. 8.Best estimate of 769 ÷ 26? (a) 260 (b) 2600 (c) 26
  9. 9.Best estimate of 2391 ÷ 49? (a) 480 (b) 4800 (c) 48
  10. 10.Best estimate of 2953 ÷ 56? (a) 49 (b) 490 (c) 4900
  11. 11.Best estimate of 639 ÷ 26? (a) 2100 (b) 21 (c) 210
  12. 12.Best estimate of 632 ÷ 32? (a) 21 (b) 210 (c) 2100
  13. 13.Best estimate of 4029 ÷ 57? (a) 6700 (b) 670 (c) 67
  14. 14.Best estimate of 3079 ÷ 61? (a) 51 (b) 5100 (c) 510
  15. 15.√43 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.6 (d) 6.5
  16. 16.Best estimate of 2178 ÷ 29? (a) 730 (b) 7300 (c) 73
  17. 17.Best estimate of 1608 ÷ 49? (a) 320 (b) 32 (c) 3200
  18. 18.Best estimate of 3128 ÷ 69? (a) 45 (b) 4500 (c) 450
  19. 19.Best estimate of 6658 ÷ 82? (a) 8300 (b) 830 (c) 83
  20. 20.Best estimate of 2026 ÷ 22? (a) 1010 (b) 10100 (c) 101
  21. 21.Best estimate of 2754 ÷ 42? (a) 690 (b) 6900 (c) 69
  22. 22.√34 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.0 (d) 6.1
  23. 23.√41 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.6 (d) 6.4
  24. 24.√75 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.7 (d) 8.4
  25. 25.Best estimate of 827 ÷ 28? (a) 280 (b) 2800 (c) 28
  26. 26.Best estimate of 7253 ÷ 78? (a) 91 (b) 910 (c) 9100
  27. 27.Best estimate of 2930 ÷ 76? (a) 3700 (b) 370 (c) 37
  28. 28.Best estimate of 2425 ÷ 44? (a) 610 (b) 6100 (c) 61
  29. 29.√98 to 1 decimal place? (a) 9.9 (b) 10.1 (c) 10.0 (d) 10.2
  30. 30.Best estimate of 3395 ÷ 57? (a) 5700 (b) 570 (c) 57
  31. 31.Best estimate of 788 ÷ 48? (a) 1600 (b) 160 (c) 16
  32. 32.Best estimate of 2206 ÷ 73? (a) 3200 (b) 32 (c) 320
  33. 33.√82 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.1
  34. 34.√86 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 9.3
  35. 35.Best estimate of 5694 ÷ 63? (a) 95 (b) 9500 (c) 950
  36. 36.Best estimate of 2213 ÷ 63? (a) 370 (b) 3700 (c) 37
  37. 37.Best estimate of 476 ÷ 23? (a) 2400 (b) 24 (c) 240
  38. 38.Best estimate of 6329 ÷ 88? (a) 700 (b) 70 (c) 7000
  39. 39.Best estimate of 696 ÷ 23? (a) 350 (b) 3500 (c) 35
  40. 40.√90 to 1 decimal place? (a) 9.3 (b) 9.6 (c) 9.5 (d) 9.4

Answer key

  1. 8.6
  2. 6.1
  3. 8.8
  4. 5.5
  5. 81
  6. 6.8
  7. 8.9
  8. 26
  9. 48
  10. 49
  11. 21
  12. 21
  13. 67
  14. 51
  15. 6.6
  16. 73
  17. 32
  18. 45
  19. 83
  20. 101
  21. 69
  22. 5.8
  23. 6.4
  24. 8.7
  25. 28
  26. 91
  27. 37
  28. 61
  29. 9.9
  30. 57
  31. 16
  32. 32
  33. 9.1
  34. 9.3
  35. 95
  36. 37
  37. 24
  38. 70
  39. 35
  40. 9.5

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