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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 690 · 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 1862 ÷ 38? (a) 4700 (b) 47 (c) 470
  2. 2.√48 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 7.0 (d) 6.9
  3. 3.√65 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.4 (d) 8.2
  4. 4.Best estimate of 2466 ÷ 56? (a) 410 (b) 4100 (c) 41
  5. 5.√29 to 1 decimal place? (a) 5.1 (b) 5.3 (c) 5.4 (d) 5.2
  6. 6.√53 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.3 (d) 7.6
  7. 7.Best estimate of 4130 ÷ 76? (a) 5200 (b) 52 (c) 520
  8. 8.√67 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.2 (d) 8.3
  9. 9.Best estimate of 946 ÷ 42? (a) 24 (b) 240 (c) 2400
  10. 10.Best estimate of 4956 ÷ 54? (a) 990 (b) 9900 (c) 99
  11. 11.Best estimate of 6292 ÷ 66? (a) 9000 (b) 900 (c) 90
  12. 12.√72 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.4 (d) 8.5
  13. 13.Best estimate of 954 ÷ 41? (a) 240 (b) 24 (c) 2400
  14. 14.Best estimate of 1335 ÷ 49? (a) 27 (b) 270 (c) 2700
  15. 15.√35 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 5.8 (d) 6.0
  16. 16.Best estimate of 4202 ÷ 84? (a) 530 (b) 53 (c) 5300
  17. 17.√42 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.5
  18. 18.√26 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  19. 19.Best estimate of 2385 ÷ 44? (a) 60 (b) 6000 (c) 600
  20. 20.Best estimate of 4078 ÷ 58? (a) 6800 (b) 680 (c) 68
  21. 21.Best estimate of 2765 ÷ 31? (a) 92 (b) 9200 (c) 920
  22. 22.Best estimate of 2907 ÷ 32? (a) 9700 (b) 970 (c) 97
  23. 23.Best estimate of 814 ÷ 27? (a) 2700 (b) 270 (c) 27
  24. 24.Best estimate of 3344 ÷ 52? (a) 670 (b) 6700 (c) 67
  25. 25.√40 to 1 decimal place? (a) 6.1 (b) 6.0 (c) 6.3 (d) 6.2
  26. 26.Best estimate of 2531 ÷ 46? (a) 51 (b) 510 (c) 5100
  27. 27.Best estimate of 1573 ÷ 82? (a) 2000 (b) 200 (c) 20
  28. 28.√21 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 4.6 (d) 4.8
  29. 29.√55 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.2 (d) 7.1
  30. 30.Best estimate of 1883 ÷ 27? (a) 630 (b) 6300 (c) 63
  31. 31.Best estimate of 839 ÷ 52? (a) 1700 (b) 17 (c) 170
  32. 32.Best estimate of 2818 ÷ 46? (a) 5600 (b) 560 (c) 56
  33. 33.Best estimate of 1332 ÷ 59? (a) 220 (b) 2200 (c) 22
  34. 34.√20 to 1 decimal place? (a) 4.2 (b) 4.3 (c) 4.5 (d) 4.4
  35. 35.Best estimate of 5029 ÷ 56? (a) 8400 (b) 84 (c) 840
  36. 36.√58 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.7
  37. 37.Best estimate of 2100 ÷ 82? (a) 260 (b) 2600 (c) 26
  38. 38.√83 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.0 (d) 9.1
  39. 39.Best estimate of 426 ÷ 27? (a) 1400 (b) 140 (c) 14
  40. 40.Best estimate of 969 ÷ 23? (a) 480 (b) 48 (c) 4800

Answer key

  1. 47
  2. 6.9
  3. 8.1
  4. 41
  5. 5.4
  6. 7.3
  7. 52
  8. 8.2
  9. 24
  10. 99
  11. 90
  12. 8.5
  13. 24
  14. 27
  15. 5.9
  16. 53
  17. 6.5
  18. 5.1
  19. 60
  20. 68
  21. 92
  22. 97
  23. 27
  24. 67
  25. 6.3
  26. 51
  27. 20
  28. 4.6
  29. 7.4
  30. 63
  31. 17
  32. 56
  33. 22
  34. 4.5
  35. 84
  36. 7.6
  37. 26
  38. 9.1
  39. 14
  40. 48

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