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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 91 · 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 2406 ÷ 69? (a) 340 (b) 3400 (c) 34
  2. 2.√94 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.8 (d) 9.6
  3. 3.√59 to 1 decimal place? (a) 7.7 (b) 7.4 (c) 7.5 (d) 7.6
  4. 4.√43 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.5 (d) 6.4
  5. 5.√88 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.4
  6. 6.Best estimate of 4146 ÷ 64? (a) 690 (b) 6900 (c) 69
  7. 7.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.0 (d) 4.9
  8. 8.Best estimate of 1352 ÷ 53? (a) 270 (b) 27 (c) 2700
  9. 9.Best estimate of 1637 ÷ 26? (a) 5500 (b) 55 (c) 550
  10. 10.√37 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.0 (d) 5.9
  11. 11.Best estimate of 1718 ÷ 22? (a) 860 (b) 8600 (c) 86
  12. 12.Best estimate of 2536 ÷ 69? (a) 36 (b) 360 (c) 3600
  13. 13.Best estimate of 4472 ÷ 62? (a) 7500 (b) 750 (c) 75
  14. 14.√92 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.7 (d) 9.5
  15. 15.Best estimate of 3716 ÷ 62? (a) 62 (b) 620 (c) 6200
  16. 16.Best estimate of 627 ÷ 47? (a) 1300 (b) 130 (c) 13
  17. 17.Best estimate of 1228 ÷ 42? (a) 3100 (b) 31 (c) 310
  18. 18.Best estimate of 2145 ÷ 23? (a) 107 (b) 10700 (c) 1070
  19. 19.√83 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 9.1 (d) 8.9
  20. 20.√35 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.8 (d) 5.9
  21. 21.√77 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.8
  22. 22.√80 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 9.1
  23. 23.Best estimate of 2128 ÷ 33? (a) 71 (b) 7100 (c) 710
  24. 24.Best estimate of 1599 ÷ 37? (a) 40 (b) 4000 (c) 400
  25. 25.Best estimate of 4366 ÷ 63? (a) 7300 (b) 73 (c) 730
  26. 26.√44 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.7
  27. 27.Best estimate of 690 ÷ 42? (a) 170 (b) 1700 (c) 17
  28. 28.Best estimate of 2207 ÷ 57? (a) 37 (b) 3700 (c) 370
  29. 29.Best estimate of 4360 ÷ 83? (a) 550 (b) 5500 (c) 55
  30. 30.Best estimate of 2609 ÷ 76? (a) 3300 (b) 33 (c) 330
  31. 31.√32 to 1 decimal place? (a) 5.8 (b) 6.0 (c) 5.9 (d) 5.7
  32. 32.√69 to 1 decimal place? (a) 8.3 (b) 8.5 (c) 8.6 (d) 8.4
  33. 33.√20 to 1 decimal place? (a) 4.6 (b) 4.8 (c) 4.5 (d) 4.7
  34. 34.Best estimate of 1723 ÷ 42? (a) 43 (b) 4300 (c) 430
  35. 35.Best estimate of 4359 ÷ 82? (a) 5400 (b) 540 (c) 54
  36. 36.Best estimate of 2521 ÷ 39? (a) 63 (b) 6300 (c) 630
  37. 37.Best estimate of 2854 ÷ 66? (a) 41 (b) 4100 (c) 410
  38. 38.Best estimate of 3867 ÷ 78? (a) 4800 (b) 480 (c) 48
  39. 39.Best estimate of 2442 ÷ 49? (a) 4900 (b) 49 (c) 490
  40. 40.√74 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.7 (d) 8.9

Answer key

  1. 34
  2. 9.7
  3. 7.7
  4. 6.6
  5. 9.4
  6. 69
  7. 5.1
  8. 27
  9. 55
  10. 6.1
  11. 86
  12. 36
  13. 75
  14. 9.6
  15. 62
  16. 13
  17. 31
  18. 107
  19. 9.1
  20. 5.9
  21. 8.8
  22. 8.9
  23. 71
  24. 40
  25. 73
  26. 6.6
  27. 17
  28. 37
  29. 55
  30. 33
  31. 5.7
  32. 8.3
  33. 4.5
  34. 43
  35. 54
  36. 63
  37. 41
  38. 48
  39. 49
  40. 8.6

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