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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 307 · 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.√22 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.8 (d) 4.6
  2. 2.√65 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.0 (d) 8.1
  3. 3.√79 to 1 decimal place? (a) 8.9 (b) 8.7 (c) 8.8 (d) 8.6
  4. 4.Best estimate of 3112 ÷ 62? (a) 52 (b) 5200 (c) 520
  5. 5.Best estimate of 1287 ÷ 64? (a) 21 (b) 210 (c) 2100
  6. 6.Best estimate of 1261 ÷ 42? (a) 32 (b) 320 (c) 3200
  7. 7.√70 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.5
  8. 8.Best estimate of 2438 ÷ 73? (a) 3500 (b) 35 (c) 350
  9. 9.√31 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.8 (d) 5.6
  10. 10.√55 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.4 (d) 7.5
  11. 11.Best estimate of 5231 ÷ 77? (a) 650 (b) 6500 (c) 65
  12. 12.√56 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.3
  13. 13.Best estimate of 2524 ÷ 83? (a) 320 (b) 32 (c) 3200
  14. 14.Best estimate of 4926 ÷ 88? (a) 55 (b) 550 (c) 5500
  15. 15.Best estimate of 1358 ÷ 26? (a) 450 (b) 45 (c) 4500
  16. 16.Best estimate of 4034 ÷ 56? (a) 67 (b) 6700 (c) 670
  17. 17.√30 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.4 (d) 5.5
  18. 18.Best estimate of 7394 ÷ 82? (a) 9200 (b) 920 (c) 92
  19. 19.Best estimate of 1149 ÷ 37? (a) 290 (b) 2900 (c) 29
  20. 20.√96 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.8
  21. 21.Best estimate of 863 ÷ 26? (a) 290 (b) 2900 (c) 29
  22. 22.Best estimate of 619 ÷ 32? (a) 21 (b) 2100 (c) 210
  23. 23.Best estimate of 1592 ÷ 59? (a) 270 (b) 27 (c) 2700
  24. 24.√40 to 1 decimal place? (a) 6.4 (b) 6.1 (c) 6.3 (d) 6.2
  25. 25.√26 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 5.0 (d) 4.8
  26. 26.√88 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.7 (d) 9.5
  27. 27.Best estimate of 7855 ÷ 87? (a) 8700 (b) 870 (c) 87
  28. 28.Best estimate of 3607 ÷ 42? (a) 900 (b) 90 (c) 9000
  29. 29.Best estimate of 4341 ÷ 52? (a) 870 (b) 87 (c) 8700
  30. 30.Best estimate of 1254 ÷ 36? (a) 31 (b) 310 (c) 3100
  31. 31.Best estimate of 1472 ÷ 57? (a) 2500 (b) 25 (c) 250
  32. 32.Best estimate of 4893 ÷ 68? (a) 70 (b) 7000 (c) 700
  33. 33.Best estimate of 3847 ÷ 42? (a) 9600 (b) 960 (c) 96
  34. 34.√94 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.5 (d) 9.7
  35. 35.Best estimate of 1738 ÷ 83? (a) 2200 (b) 220 (c) 22
  36. 36.√71 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.5
  37. 37.Best estimate of 2491 ÷ 29? (a) 8300 (b) 83 (c) 830
  38. 38.√98 to 1 decimal place? (a) 10.0 (b) 9.7 (c) 9.9 (d) 9.8
  39. 39.Best estimate of 1940 ÷ 29? (a) 650 (b) 65 (c) 6500
  40. 40.Best estimate of 8414 ÷ 88? (a) 9300 (b) 930 (c) 93

Answer key

  1. 4.7
  2. 8.1
  3. 8.9
  4. 52
  5. 21
  6. 32
  7. 8.4
  8. 35
  9. 5.6
  10. 7.4
  11. 65
  12. 7.5
  13. 32
  14. 55
  15. 45
  16. 67
  17. 5.5
  18. 92
  19. 29
  20. 9.8
  21. 29
  22. 21
  23. 27
  24. 6.3
  25. 5.1
  26. 9.4
  27. 87
  28. 90
  29. 87
  30. 31
  31. 25
  32. 70
  33. 96
  34. 9.7
  35. 22
  36. 8.4
  37. 83
  38. 9.9
  39. 65
  40. 93

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