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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 429 · 40 questions
TalentJR

The trick (Seventh times eleven): A leapfrog list: start with two numbers, then each number is the sum of the two before it, up to 10 numbers. Find the 7th number. Multiply it by 11 (the number with a 0 on the end, plus the number): that is the total of all 10.

NameDateTime takenScore ___ / 40
  1. 1.Leapfrog list (each number is the sum of the two before it): 5, 5, 10, 15, 25, 40, 65, 105, 170, 275. What is 11 × the 7th number?
  2. 2.A leapfrog list starts 1, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  4. 4.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  5. 5.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  6. 6.Leapfrog list (each number is the sum of the two before it): 6, 4, 10, 14, 24, 38, 62, 100, 162, 262. What is 11 × the 7th number?
  7. 7.Leapfrog list (each number is the sum of the two before it): 3, 8, 11, 19, 30, 49, 79, 128, 207, 335. What is 11 × the 7th number?
  8. 8.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  9. 9.Leapfrog list (each number is the sum of the two before it): 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is 11 × the 7th number?
  10. 10.Leapfrog list (each number is the sum of the two before it): 2, 7, 9, 16, 25, 41, 66, 107, 173, 280. What is 11 × the 7th number?
  11. 11.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  12. 12.Leapfrog list (each number is the sum of the two before it): 7, 4, 11, 15, 26, 41, 67, 108, 175, 283. What is 11 × the 7th number?
  13. 13.A leapfrog list starts 2, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.A leapfrog list starts 9, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  16. 16.Leapfrog list (each number is the sum of the two before it): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  17. 17.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  18. 18.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 5, 9, 14, 23, 37, 60, 97, 157, 254, 411. What is 11 × the 7th number?
  20. 20.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  21. 21.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  22. 22.A leapfrog list starts 6, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  23. 23.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
  24. 24.A leapfrog list starts 9, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.Leapfrog list (each number is the sum of the two before it): 8, 7, 15, 22, 37, 59, 96, 155, 251, 406. What is 11 × the 7th number?
  26. 26.Leapfrog list (each number is the sum of the two before it): 3, 4, 7, 11, 18, 29, 47, 76, 123, 199. What is 11 × the 7th number?
  27. 27.A leapfrog list starts 3, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  29. 29.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  30. 30.Leapfrog list (each number is the sum of the two before it): 9, 1, 10, 11, 21, 32, 53, 85, 138, 223. What is 11 × the 7th number?
  31. 31.A leapfrog list starts 7, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.Leapfrog list (each number is the sum of the two before it): 1, 3, 4, 7, 11, 18, 29, 47, 76, 123. What is 11 × the 7th number?
  33. 33.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  34. 34.Leapfrog list (each number is the sum of the two before it): 2, 4, 6, 10, 16, 26, 42, 68, 110, 178. What is 11 × the 7th number?
  35. 35.Leapfrog list (each number is the sum of the two before it): 1, 9, 10, 19, 29, 48, 77, 125, 202, 327. What is 11 × the 7th number?
  36. 36.A leapfrog list starts 3, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  38. 38.A leapfrog list starts 6, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.Leapfrog list (each number is the sum of the two before it): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  40. 40.Leapfrog list (each number is the sum of the two before it): 7, 9, 16, 25, 41, 66, 107, 173, 280, 453. What is 11 × the 7th number?

Answer key

  1. 715
  2. 319
  3. 704
  4. 847
  5. 451
  6. 682
  7. 869
  8. 781
  9. 231
  10. 726
  11. 968
  12. 737
  13. 902
  14. 1111
  15. 484
  16. 759
  17. 1199
  18. 1034
  19. 1067
  20. 550
  21. 1056
  22. 506
  23. 1144
  24. 935
  25. 1056
  26. 517
  27. 517
  28. 880
  29. 539
  30. 583
  31. 1089
  32. 319
  33. 605
  34. 462
  35. 847
  36. 693
  37. 583
  38. 1122
  39. 451
  40. 1177

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