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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 778 · 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 5046 ÷ 53? (a) 10100 (b) 1010 (c) 101
  2. 2.Best estimate of 2972 ÷ 46? (a) 59 (b) 5900 (c) 590
  3. 3.√23 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 5.1 (d) 5.0
  4. 4.Best estimate of 2424 ÷ 59? (a) 4000 (b) 40 (c) 400
  5. 5.Best estimate of 1040 ÷ 68? (a) 1500 (b) 15 (c) 150
  6. 6.Best estimate of 4580 ÷ 52? (a) 9200 (b) 92 (c) 920
  7. 7.√65 to 1 decimal place? (a) 7.9 (b) 8.1 (c) 7.8 (d) 8.0
  8. 8.√55 to 1 decimal place? (a) 7.7 (b) 7.5 (c) 7.4 (d) 7.6
  9. 9.√22 to 1 decimal place? (a) 5.0 (b) 4.7 (c) 4.8 (d) 4.9
  10. 10.Best estimate of 884 ÷ 57? (a) 150 (b) 15 (c) 1500
  11. 11.Best estimate of 3100 ÷ 56? (a) 520 (b) 5200 (c) 52
  12. 12.√78 to 1 decimal place? (a) 8.9 (b) 9.0 (c) 8.7 (d) 8.8
  13. 13.√72 to 1 decimal place? (a) 8.4 (b) 8.7 (c) 8.6 (d) 8.5
  14. 14.√51 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.4 (d) 7.1
  15. 15.Best estimate of 3022 ÷ 42? (a) 76 (b) 760 (c) 7600
  16. 16.√67 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.2 (d) 8.3
  17. 17.Best estimate of 1437 ÷ 66? (a) 210 (b) 2100 (c) 21
  18. 18.√70 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.4
  19. 19.√98 to 1 decimal place? (a) 10.2 (b) 10.1 (c) 9.9 (d) 10.0
  20. 20.Best estimate of 1783 ÷ 31? (a) 59 (b) 590 (c) 5900
  21. 21.√53 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.0 (d) 7.1
  22. 22.Best estimate of 1376 ÷ 82? (a) 17 (b) 1700 (c) 170
  23. 23.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.1 (d) 5.2
  24. 24.Best estimate of 2135 ÷ 73? (a) 310 (b) 31 (c) 3100
  25. 25.Best estimate of 1436 ÷ 71? (a) 21 (b) 210 (c) 2100
  26. 26.Best estimate of 912 ÷ 26? (a) 3000 (b) 300 (c) 30
  27. 27.Best estimate of 1266 ÷ 24? (a) 6300 (b) 630 (c) 63
  28. 28.Best estimate of 2547 ÷ 36? (a) 64 (b) 640 (c) 6400
  29. 29.Best estimate of 2521 ÷ 42? (a) 630 (b) 63 (c) 6300
  30. 30.Best estimate of 4960 ÷ 62? (a) 83 (b) 830 (c) 8300
  31. 31.Best estimate of 2139 ÷ 84? (a) 270 (b) 2700 (c) 27
  32. 32.Best estimate of 771 ÷ 52? (a) 1500 (b) 150 (c) 15
  33. 33.Best estimate of 2474 ÷ 27? (a) 82 (b) 820 (c) 8200
  34. 34.√82 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 8.8 (d) 9.1
  35. 35.√63 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.7 (d) 7.6
  36. 36.Best estimate of 5043 ÷ 69? (a) 72 (b) 7200 (c) 720
  37. 37.Best estimate of 7612 ÷ 82? (a) 95 (b) 9500 (c) 950
  38. 38.Best estimate of 2751 ÷ 89? (a) 31 (b) 310 (c) 3100
  39. 39.Best estimate of 1517 ÷ 74? (a) 2200 (b) 22 (c) 220
  40. 40.Best estimate of 730 ÷ 23? (a) 3700 (b) 37 (c) 370

Answer key

  1. 101
  2. 59
  3. 4.8
  4. 40
  5. 15
  6. 92
  7. 8.1
  8. 7.4
  9. 4.7
  10. 15
  11. 52
  12. 8.8
  13. 8.5
  14. 7.1
  15. 76
  16. 8.2
  17. 21
  18. 8.4
  19. 9.9
  20. 59
  21. 7.3
  22. 17
  23. 5.1
  24. 31
  25. 21
  26. 30
  27. 63
  28. 64
  29. 63
  30. 83
  31. 27
  32. 15
  33. 82
  34. 9.1
  35. 7.9
  36. 72
  37. 95
  38. 31
  39. 22
  40. 37

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