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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 386 · 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 1633 ÷ 66? (a) 2300 (b) 23 (c) 230
  2. 2.√78 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 8.8
  3. 3.Best estimate of 3182 ÷ 39? (a) 8000 (b) 800 (c) 80
  4. 4.Best estimate of 1334 ÷ 83? (a) 170 (b) 1700 (c) 17
  5. 5.√23 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 4.6 (d) 4.7
  6. 6.Best estimate of 4849 ÷ 83? (a) 610 (b) 6100 (c) 61
  7. 7.√42 to 1 decimal place? (a) 6.7 (b) 6.4 (c) 6.6 (d) 6.5
  8. 8.√30 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.8 (d) 5.5
  9. 9.Best estimate of 1927 ÷ 63? (a) 3200 (b) 32 (c) 320
  10. 10.Best estimate of 1179 ÷ 26? (a) 390 (b) 39 (c) 3900
  11. 11.Best estimate of 4517 ÷ 52? (a) 900 (b) 9000 (c) 90
  12. 12.√96 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 9.9 (d) 9.7
  13. 13.√32 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.5 (d) 5.8
  14. 14.√40 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.2
  15. 15.Best estimate of 1491 ÷ 66? (a) 21 (b) 2100 (c) 210
  16. 16.Best estimate of 1966 ÷ 64? (a) 3300 (b) 330 (c) 33
  17. 17.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.9 (d) 5.8
  18. 18.√69 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.3 (d) 8.1
  19. 19.√87 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.1 (d) 9.4
  20. 20.Best estimate of 4021 ÷ 47? (a) 800 (b) 8000 (c) 80
  21. 21.Best estimate of 1861 ÷ 46? (a) 37 (b) 3700 (c) 370
  22. 22.Best estimate of 4836 ÷ 61? (a) 810 (b) 8100 (c) 81
  23. 23.√43 to 1 decimal place? (a) 6.3 (b) 6.6 (c) 6.4 (d) 6.5
  24. 24.Best estimate of 620 ÷ 26? (a) 210 (b) 21 (c) 2100
  25. 25.Best estimate of 2929 ÷ 72? (a) 42 (b) 4200 (c) 420
  26. 26.Best estimate of 1598 ÷ 49? (a) 320 (b) 3200 (c) 32
  27. 27.Best estimate of 1599 ÷ 28? (a) 5300 (b) 530 (c) 53
  28. 28.Best estimate of 2248 ÷ 64? (a) 3700 (b) 37 (c) 370
  29. 29.√48 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.0 (d) 6.9
  30. 30.Best estimate of 2379 ÷ 66? (a) 340 (b) 34 (c) 3400
  31. 31.√61 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  32. 32.Best estimate of 1705 ÷ 42? (a) 430 (b) 43 (c) 4300
  33. 33.√45 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 6.8 (d) 6.7
  34. 34.Best estimate of 5239 ÷ 73? (a) 750 (b) 75 (c) 7500
  35. 35.√53 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.3 (d) 7.4
  36. 36.Best estimate of 3935 ÷ 57? (a) 660 (b) 66 (c) 6600
  37. 37.Best estimate of 1569 ÷ 66? (a) 220 (b) 2200 (c) 22
  38. 38.Best estimate of 1707 ÷ 21? (a) 85 (b) 8500 (c) 850
  39. 39.√88 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.5 (d) 9.7
  40. 40.Best estimate of 2972 ÷ 71? (a) 4200 (b) 42 (c) 420

Answer key

  1. 23
  2. 8.8
  3. 80
  4. 17
  5. 4.8
  6. 61
  7. 6.5
  8. 5.5
  9. 32
  10. 39
  11. 90
  12. 9.8
  13. 5.7
  14. 6.3
  15. 21
  16. 33
  17. 5.8
  18. 8.3
  19. 9.3
  20. 80
  21. 37
  22. 81
  23. 6.6
  24. 21
  25. 42
  26. 32
  27. 53
  28. 37
  29. 6.9
  30. 34
  31. 7.8
  32. 43
  33. 6.7
  34. 75
  35. 7.3
  36. 66
  37. 22
  38. 85
  39. 9.4
  40. 42

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