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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 243 · 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 1396 ÷ 86? (a) 1600 (b) 160 (c) 16
  2. 2.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.2 (d) 6.5
  3. 3.Best estimate of 7707 ÷ 86? (a) 86 (b) 8600 (c) 860
  4. 4.√92 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.5
  5. 5.√87 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.2
  6. 6.√89 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.5
  7. 7.Best estimate of 4780 ÷ 62? (a) 8000 (b) 80 (c) 800
  8. 8.Best estimate of 1055 ÷ 41? (a) 2600 (b) 26 (c) 260
  9. 9.Best estimate of 1607 ÷ 51? (a) 320 (b) 3200 (c) 32
  10. 10.Best estimate of 504 ÷ 42? (a) 130 (b) 1300 (c) 13
  11. 11.Best estimate of 2048 ÷ 22? (a) 1020 (b) 10200 (c) 102
  12. 12.√62 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  13. 13.Best estimate of 2662 ÷ 61? (a) 4400 (b) 440 (c) 44
  14. 14.Best estimate of 1582 ÷ 49? (a) 320 (b) 3200 (c) 32
  15. 15.√22 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.4 (d) 4.6
  16. 16.√20 to 1 decimal place? (a) 4.3 (b) 4.4 (c) 4.5 (d) 4.6
  17. 17.Best estimate of 1440 ÷ 86? (a) 16 (b) 160 (c) 1600
  18. 18.√38 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.4 (d) 6.1
  19. 19.Best estimate of 6529 ÷ 88? (a) 73 (b) 730 (c) 7300
  20. 20.√58 to 1 decimal place? (a) 7.5 (b) 7.3 (c) 7.4 (d) 7.6
  21. 21.Best estimate of 2307 ÷ 83? (a) 290 (b) 2900 (c) 29
  22. 22.Best estimate of 959 ÷ 72? (a) 1400 (b) 140 (c) 14
  23. 23.√23 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 4.6
  24. 24.√50 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.8 (d) 6.9
  25. 25.√28 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.5 (d) 5.4
  26. 26.Best estimate of 1521 ÷ 79? (a) 190 (b) 1900 (c) 19
  27. 27.√37 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.4 (d) 6.1
  28. 28.√65 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 8.0 (d) 8.1
  29. 29.Best estimate of 1194 ÷ 27? (a) 400 (b) 4000 (c) 40
  30. 30.Best estimate of 628 ÷ 23? (a) 31 (b) 3100 (c) 310
  31. 31.√98 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 9.6
  32. 32.Best estimate of 6795 ÷ 74? (a) 97 (b) 970 (c) 9700
  33. 33.Best estimate of 2299 ÷ 81? (a) 290 (b) 29 (c) 2900
  34. 34.Best estimate of 1173 ÷ 28? (a) 390 (b) 39 (c) 3900
  35. 35.Best estimate of 674 ÷ 23? (a) 340 (b) 3400 (c) 34
  36. 36.Best estimate of 5489 ÷ 63? (a) 910 (b) 9100 (c) 91
  37. 37.Best estimate of 2345 ÷ 59? (a) 390 (b) 39 (c) 3900
  38. 38.Best estimate of 1202 ÷ 41? (a) 300 (b) 30 (c) 3000
  39. 39.Best estimate of 2566 ÷ 36? (a) 64 (b) 640 (c) 6400
  40. 40.√27 to 1 decimal place? (a) 5.3 (b) 5.5 (c) 5.4 (d) 5.2

Answer key

  1. 16
  2. 6.3
  3. 86
  4. 9.6
  5. 9.3
  6. 9.4
  7. 80
  8. 26
  9. 32
  10. 13
  11. 102
  12. 7.9
  13. 44
  14. 32
  15. 4.7
  16. 4.5
  17. 16
  18. 6.2
  19. 73
  20. 7.6
  21. 29
  22. 14
  23. 4.8
  24. 7.1
  25. 5.3
  26. 19
  27. 6.1
  28. 8.1
  29. 40
  30. 31
  31. 9.9
  32. 97
  33. 29
  34. 39
  35. 34
  36. 91
  37. 39
  38. 30
  39. 64
  40. 5.2

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