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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 368 · 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 4386 ÷ 63? (a) 7300 (b) 73 (c) 730
  2. 2.√89 to 1 decimal place? (a) 9.3 (b) 9.6 (c) 9.5 (d) 9.4
  3. 3.Best estimate of 3572 ÷ 51? (a) 7100 (b) 710 (c) 71
  4. 4.Best estimate of 828 ÷ 27? (a) 280 (b) 2800 (c) 28
  5. 5.Best estimate of 1838 ÷ 52? (a) 37 (b) 370 (c) 3700
  6. 6.√98 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.6 (d) 9.7
  7. 7.Best estimate of 2415 ÷ 72? (a) 3500 (b) 350 (c) 35
  8. 8.Best estimate of 1773 ÷ 76? (a) 220 (b) 2200 (c) 22
  9. 9.√32 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.9
  10. 10.√92 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.5
  11. 11.Best estimate of 4209 ÷ 78? (a) 53 (b) 530 (c) 5300
  12. 12.Best estimate of 632 ÷ 32? (a) 210 (b) 21 (c) 2100
  13. 13.Best estimate of 1835 ÷ 66? (a) 26 (b) 2600 (c) 260
  14. 14.Best estimate of 3250 ÷ 41? (a) 810 (b) 81 (c) 8100
  15. 15.Best estimate of 1252 ÷ 87? (a) 14 (b) 1400 (c) 140
  16. 16.Best estimate of 1458 ÷ 36? (a) 360 (b) 3600 (c) 36
  17. 17.√94 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.8 (d) 9.7
  18. 18.Best estimate of 943 ÷ 54? (a) 190 (b) 19 (c) 1900
  19. 19.Best estimate of 2038 ÷ 89? (a) 23 (b) 2300 (c) 230
  20. 20.Best estimate of 1282 ÷ 32? (a) 43 (b) 430 (c) 4300
  21. 21.Best estimate of 1289 ÷ 32? (a) 4300 (b) 43 (c) 430
  22. 22.√23 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.5
  23. 23.Best estimate of 2381 ÷ 74? (a) 34 (b) 3400 (c) 340
  24. 24.√70 to 1 decimal place? (a) 8.7 (b) 8.4 (c) 8.6 (d) 8.5
  25. 25.Best estimate of 3337 ÷ 37? (a) 8300 (b) 83 (c) 830
  26. 26.Best estimate of 2296 ÷ 39? (a) 57 (b) 5700 (c) 570
  27. 27.Best estimate of 2426 ÷ 38? (a) 610 (b) 6100 (c) 61
  28. 28.Best estimate of 2407 ÷ 26? (a) 800 (b) 80 (c) 8000
  29. 29.√84 to 1 decimal place? (a) 9.2 (b) 9.0 (c) 8.9 (d) 9.1
  30. 30.√74 to 1 decimal place? (a) 8.5 (b) 8.6 (c) 8.7 (d) 8.4
  31. 31.√61 to 1 decimal place? (a) 8.1 (b) 7.8 (c) 8.0 (d) 7.9
  32. 32.Best estimate of 1855 ÷ 71? (a) 27 (b) 270 (c) 2700
  33. 33.Best estimate of 979 ÷ 51? (a) 200 (b) 20 (c) 2000
  34. 34.√79 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 8.8 (d) 8.9
  35. 35.√21 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.6 (d) 4.9
  36. 36.√67 to 1 decimal place? (a) 8.4 (b) 8.3 (c) 8.2 (d) 8.5
  37. 37.√31 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.3
  38. 38.Best estimate of 1904 ÷ 44? (a) 480 (b) 4800 (c) 48
  39. 39.√51 to 1 decimal place? (a) 7.0 (b) 6.8 (c) 6.9 (d) 7.1
  40. 40.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.3 (d) 5.0

Answer key

  1. 73
  2. 9.4
  3. 71
  4. 28
  5. 37
  6. 9.9
  7. 35
  8. 22
  9. 5.7
  10. 9.6
  11. 53
  12. 21
  13. 26
  14. 81
  15. 14
  16. 36
  17. 9.7
  18. 19
  19. 23
  20. 43
  21. 43
  22. 4.8
  23. 34
  24. 8.4
  25. 83
  26. 57
  27. 61
  28. 80
  29. 9.2
  30. 8.6
  31. 7.8
  32. 27
  33. 20
  34. 8.9
  35. 4.6
  36. 8.2
  37. 5.6
  38. 48
  39. 7.1
  40. 5.1

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