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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 629 · 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): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 7, 2, 9, 11, 20, 31, 51, 82, 133, 215. What is 11 × the 7th number?
  3. 3.A leapfrog list starts 4, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  4. 4.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  5. 5.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  6. 6.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.A leapfrog list starts 2, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  8. 8.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  9. 9.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  10. 10.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  11. 11.Leapfrog list (each number is the sum of the two before it): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  12. 12.Leapfrog list (each number is the sum of the two before it): 5, 7, 12, 19, 31, 50, 81, 131, 212, 343. What is 11 × the 7th number?
  13. 13.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  14. 14.Leapfrog list (each number is the sum of the two before it): 6, 8, 14, 22, 36, 58, 94, 152, 246, 398. What is 11 × the 7th number?
  15. 15.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?
  16. 16.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  17. 17.Leapfrog list (each number is the sum of the two before it): 9, 9, 18, 27, 45, 72, 117, 189, 306, 495. What is 11 × the 7th number?
  18. 18.A leapfrog list starts 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.A leapfrog list starts 5, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.Leapfrog list (each number is the sum of the two before it): 2, 1, 3, 4, 7, 11, 18, 29, 47, 76. What is 11 × the 7th number?
  21. 21.A leapfrog list starts 3, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  23. 23.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  24. 24.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?
  25. 25.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  26. 26.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 3, 1, 4, 5, 9, 14, 23, 37, 60, 97. What is 11 × the 7th number?
  28. 28.A leapfrog list starts 5, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
  30. 30.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  31. 31.Leapfrog list (each number is the sum of the two before it): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  32. 32.Leapfrog list (each number is the sum of the two before it): 7, 3, 10, 13, 23, 36, 59, 95, 154, 249. What is 11 × the 7th number?
  33. 33.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  34. 34.A leapfrog list starts 2, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.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?
  36. 36.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  37. 37.Leapfrog list (each number is the sum of the two before it): 5, 6, 11, 17, 28, 45, 73, 118, 191, 309. What is 11 × the 7th number?
  38. 38.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  39. 39.A leapfrog list starts 5, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  40. 40.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?

Answer key

  1. 616
  2. 561
  3. 748
  4. 253
  5. 231
  6. 341
  7. 550
  8. 396
  9. 517
  10. 374
  11. 341
  12. 891
  13. 341
  14. 1034
  15. 682
  16. 704
  17. 1287
  18. 561
  19. 715
  20. 198
  21. 429
  22. 528
  23. 869
  24. 1144
  25. 858
  26. 814
  27. 253
  28. 803
  29. 946
  30. 693
  31. 286
  32. 649
  33. 847
  34. 198
  35. 869
  36. 319
  37. 803
  38. 1199
  39. 451
  40. 726

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