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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 579 · 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 2917 ÷ 56? (a) 4900 (b) 490 (c) 49
  2. 2.Best estimate of 1356 ÷ 27? (a) 450 (b) 45 (c) 4500
  3. 3.Best estimate of 1332 ÷ 28? (a) 44 (b) 440 (c) 4400
  4. 4.Best estimate of 3555 ÷ 69? (a) 510 (b) 51 (c) 5100
  5. 5.√43 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.3
  6. 6.√69 to 1 decimal place? (a) 8.5 (b) 8.4 (c) 8.6 (d) 8.3
  7. 7.Best estimate of 4958 ÷ 82? (a) 6200 (b) 62 (c) 620
  8. 8.√21 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 4.6 (d) 4.7
  9. 9.Best estimate of 607 ÷ 44? (a) 1500 (b) 15 (c) 150
  10. 10.√40 to 1 decimal place? (a) 6.2 (b) 6.0 (c) 6.1 (d) 6.3
  11. 11.Best estimate of 3402 ÷ 54? (a) 6800 (b) 680 (c) 68
  12. 12.√24 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.2 (d) 5.1
  13. 13.Best estimate of 4143 ÷ 67? (a) 59 (b) 590 (c) 5900
  14. 14.Best estimate of 3354 ÷ 62? (a) 5600 (b) 560 (c) 56
  15. 15.Best estimate of 2443 ÷ 82? (a) 3100 (b) 310 (c) 31
  16. 16.√31 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.4 (d) 5.7
  17. 17.√22 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 5.0 (d) 4.9
  18. 18.Best estimate of 838 ÷ 67? (a) 12 (b) 120 (c) 1200
  19. 19.Best estimate of 3162 ÷ 46? (a) 63 (b) 6300 (c) 630
  20. 20.√74 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.5
  21. 21.Best estimate of 3090 ÷ 42? (a) 770 (b) 7700 (c) 77
  22. 22.Best estimate of 2433 ÷ 79? (a) 3000 (b) 300 (c) 30
  23. 23.√51 to 1 decimal place? (a) 7.3 (b) 7.0 (c) 7.2 (d) 7.1
  24. 24.Best estimate of 4389 ÷ 88? (a) 49 (b) 490 (c) 4900
  25. 25.√70 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.4 (d) 8.6
  26. 26.Best estimate of 1196 ÷ 54? (a) 24 (b) 240 (c) 2400
  27. 27.√89 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.2 (d) 9.4
  28. 28.Best estimate of 3292 ÷ 86? (a) 37 (b) 3700 (c) 370
  29. 29.√63 to 1 decimal place? (a) 8.2 (b) 8.0 (c) 7.9 (d) 8.1
  30. 30.√37 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.0 (d) 6.2
  31. 31.Best estimate of 794 ÷ 61? (a) 1300 (b) 130 (c) 13
  32. 32.Best estimate of 2086 ÷ 56? (a) 3500 (b) 350 (c) 35
  33. 33.Best estimate of 8503 ÷ 89? (a) 940 (b) 94 (c) 9400
  34. 34.Best estimate of 3348 ÷ 52? (a) 670 (b) 6700 (c) 67
  35. 35.Best estimate of 2399 ÷ 34? (a) 80 (b) 8000 (c) 800
  36. 36.√48 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.8 (d) 7.1
  37. 37.Best estimate of 1717 ÷ 57? (a) 290 (b) 2900 (c) 29
  38. 38.Best estimate of 3411 ÷ 41? (a) 85 (b) 850 (c) 8500
  39. 39.Best estimate of 841 ÷ 62? (a) 1400 (b) 14 (c) 140
  40. 40.√46 to 1 decimal place? (a) 6.9 (b) 6.8 (c) 6.6 (d) 6.7

Answer key

  1. 49
  2. 45
  3. 44
  4. 51
  5. 6.6
  6. 8.3
  7. 62
  8. 4.6
  9. 15
  10. 6.3
  11. 68
  12. 4.9
  13. 59
  14. 56
  15. 31
  16. 5.6
  17. 4.7
  18. 12
  19. 63
  20. 8.6
  21. 77
  22. 30
  23. 7.1
  24. 49
  25. 8.4
  26. 24
  27. 9.4
  28. 37
  29. 7.9
  30. 6.1
  31. 13
  32. 35
  33. 94
  34. 67
  35. 80
  36. 6.9
  37. 29
  38. 85
  39. 14
  40. 6.8

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