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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 114 · 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 2612 ÷ 34? (a) 870 (b) 8700 (c) 87
  2. 2.√26 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.0 (d) 4.8
  3. 3.Best estimate of 2640 ÷ 36? (a) 66 (b) 660 (c) 6600
  4. 4.Best estimate of 516 ÷ 41? (a) 13 (b) 1300 (c) 130
  5. 5.√84 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.2
  6. 6.Best estimate of 2175 ÷ 32? (a) 7300 (b) 73 (c) 730
  7. 7.Best estimate of 1174 ÷ 63? (a) 200 (b) 20 (c) 2000
  8. 8.Best estimate of 6317 ÷ 89? (a) 700 (b) 70 (c) 7000
  9. 9.√75 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.6 (d) 8.8
  10. 10.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.0 (d) 5.9
  11. 11.√85 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 9.0 (d) 9.2
  12. 12.Best estimate of 2207 ÷ 74? (a) 32 (b) 320 (c) 3200
  13. 13.√41 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.3 (d) 6.4
  14. 14.√42 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.7 (d) 6.5
  15. 15.√61 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.8
  16. 16.√66 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  17. 17.Best estimate of 1361 ÷ 59? (a) 2300 (b) 230 (c) 23
  18. 18.Best estimate of 3819 ÷ 76? (a) 48 (b) 4800 (c) 480
  19. 19.Best estimate of 1522 ÷ 28? (a) 51 (b) 5100 (c) 510
  20. 20.√20 to 1 decimal place? (a) 4.3 (b) 4.2 (c) 4.5 (d) 4.4
  21. 21.Best estimate of 3554 ÷ 47? (a) 710 (b) 7100 (c) 71
  22. 22.Best estimate of 1002 ÷ 39? (a) 250 (b) 2500 (c) 25
  23. 23.√44 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.7 (d) 6.4
  24. 24.Best estimate of 2810 ÷ 72? (a) 400 (b) 4000 (c) 40
  25. 25.Best estimate of 1957 ÷ 71? (a) 28 (b) 2800 (c) 280
  26. 26.Best estimate of 2446 ÷ 29? (a) 82 (b) 8200 (c) 820
  27. 27.Best estimate of 3830 ÷ 71? (a) 550 (b) 55 (c) 5500
  28. 28.√88 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.4
  29. 29.Best estimate of 2366 ÷ 59? (a) 390 (b) 39 (c) 3900
  30. 30.Best estimate of 816 ÷ 36? (a) 20 (b) 2000 (c) 200
  31. 31.Best estimate of 1223 ÷ 67? (a) 170 (b) 17 (c) 1700
  32. 32.√58 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  33. 33.Best estimate of 3921 ÷ 84? (a) 49 (b) 4900 (c) 490
  34. 34.√90 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.5 (d) 9.4
  35. 35.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.6 (d) 9.7
  36. 36.Best estimate of 2619 ÷ 29? (a) 87 (b) 8700 (c) 870
  37. 37.Best estimate of 1200 ÷ 52? (a) 24 (b) 2400 (c) 240
  38. 38.√46 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.6 (d) 6.9
  39. 39.Best estimate of 1723 ÷ 79? (a) 220 (b) 2200 (c) 22
  40. 40.√62 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 7.9

Answer key

  1. 87
  2. 5.1
  3. 66
  4. 13
  5. 9.2
  6. 73
  7. 20
  8. 70
  9. 8.7
  10. 6.1
  11. 9.2
  12. 32
  13. 6.4
  14. 6.5
  15. 7.8
  16. 8.1
  17. 23
  18. 48
  19. 51
  20. 4.5
  21. 71
  22. 25
  23. 6.6
  24. 40
  25. 28
  26. 82
  27. 55
  28. 9.4
  29. 39
  30. 20
  31. 17
  32. 7.6
  33. 49
  34. 9.5
  35. 9.9
  36. 87
  37. 24
  38. 6.8
  39. 22
  40. 7.9

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