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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 473 · 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.√46 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.8 (d) 6.9
  2. 2.√79 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.6 (d) 8.9
  3. 3.Best estimate of 2932 ÷ 31? (a) 9800 (b) 98 (c) 980
  4. 4.√28 to 1 decimal place? (a) 5.5 (b) 5.4 (c) 5.3 (d) 5.2
  5. 5.√86 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.4
  6. 6.Best estimate of 2417 ÷ 62? (a) 4000 (b) 400 (c) 40
  7. 7.Best estimate of 1012 ÷ 21? (a) 5100 (b) 51 (c) 510
  8. 8.√63 to 1 decimal place? (a) 7.9 (b) 8.2 (c) 8.0 (d) 8.1
  9. 9.√43 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.7 (d) 6.5
  10. 10.Best estimate of 2220 ÷ 37? (a) 5600 (b) 560 (c) 56
  11. 11.√53 to 1 decimal place? (a) 7.3 (b) 7.6 (c) 7.5 (d) 7.4
  12. 12.Best estimate of 4216 ÷ 59? (a) 700 (b) 7000 (c) 70
  13. 13.Best estimate of 1897 ÷ 47? (a) 38 (b) 3800 (c) 380
  14. 14.Best estimate of 4921 ÷ 53? (a) 980 (b) 9800 (c) 98
  15. 15.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.5 (d) 9.4
  16. 16.Best estimate of 1156 ÷ 36? (a) 29 (b) 290 (c) 2900
  17. 17.Best estimate of 4365 ÷ 52? (a) 870 (b) 87 (c) 8700
  18. 18.Best estimate of 1252 ÷ 23? (a) 63 (b) 630 (c) 6300
  19. 19.Best estimate of 1543 ÷ 42? (a) 390 (b) 3900 (c) 39
  20. 20.√92 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.5
  21. 21.Best estimate of 1442 ÷ 34? (a) 4800 (b) 480 (c) 48
  22. 22.Best estimate of 2327 ÷ 86? (a) 26 (b) 2600 (c) 260
  23. 23.Best estimate of 3256 ÷ 36? (a) 81 (b) 8100 (c) 810
  24. 24.Best estimate of 1126 ÷ 74? (a) 160 (b) 16 (c) 1600
  25. 25.Best estimate of 3874 ÷ 73? (a) 550 (b) 5500 (c) 55
  26. 26.Best estimate of 3582 ÷ 52? (a) 7200 (b) 72 (c) 720
  27. 27.Best estimate of 2299 ÷ 47? (a) 46 (b) 4600 (c) 460
  28. 28.Best estimate of 2762 ÷ 32? (a) 9200 (b) 920 (c) 92
  29. 29.Best estimate of 1931 ÷ 38? (a) 4800 (b) 480 (c) 48
  30. 30.√67 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.5
  31. 31.Best estimate of 1612 ÷ 31? (a) 540 (b) 54 (c) 5400
  32. 32.Best estimate of 1438 ÷ 36? (a) 36 (b) 360 (c) 3600
  33. 33.√83 to 1 decimal place? (a) 8.9 (b) 9.2 (c) 9.0 (d) 9.1
  34. 34.√21 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 4.6 (d) 4.8
  35. 35.√59 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.0 (d) 7.7
  36. 36.Best estimate of 5541 ÷ 83? (a) 69 (b) 6900 (c) 690
  37. 37.Best estimate of 3522 ÷ 69? (a) 50 (b) 500 (c) 5000
  38. 38.Best estimate of 2522 ÷ 66? (a) 360 (b) 3600 (c) 36
  39. 39.√42 to 1 decimal place? (a) 6.3 (b) 6.5 (c) 6.2 (d) 6.4
  40. 40.√72 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.7 (d) 8.4

Answer key

  1. 6.8
  2. 8.9
  3. 98
  4. 5.3
  5. 9.3
  6. 40
  7. 51
  8. 7.9
  9. 6.6
  10. 56
  11. 7.3
  12. 70
  13. 38
  14. 98
  15. 9.7
  16. 29
  17. 87
  18. 63
  19. 39
  20. 9.6
  21. 48
  22. 26
  23. 81
  24. 16
  25. 55
  26. 72
  27. 46
  28. 92
  29. 48
  30. 8.2
  31. 54
  32. 36
  33. 9.1
  34. 4.6
  35. 7.7
  36. 69
  37. 50
  38. 36
  39. 6.5
  40. 8.5

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