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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 200 · 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. 1.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  2. 2.Leapfrog list (each number is the sum of the two before it): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  3. 3.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  4. 4.A leapfrog list starts 5, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.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?
  6. 6.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  7. 7.Leapfrog list (each number is the sum of the two before it): 7, 5, 12, 17, 29, 46, 75, 121, 196, 317. What is 11 × the 7th number?
  8. 8.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  9. 9.A leapfrog list starts 9, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.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?
  11. 11.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  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. 13.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  14. 14.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  15. 15.A leapfrog list starts 9, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.Leapfrog list (each number is the sum of the two before it): 4, 4, 8, 12, 20, 32, 52, 84, 136, 220. What is 11 × the 7th number?
  17. 17.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?
  18. 18.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 9, 7, 16, 23, 39, 62, 101, 163, 264, 427. What is 11 × the 7th number?
  20. 20.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  21. 21.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  22. 22.A leapfrog list starts 4, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  23. 23.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  24. 24.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  25. 25.Leapfrog list (each number is the sum of the two before it): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?
  26. 26.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  27. 27.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?
  28. 28.Leapfrog list (each number is the sum of the two before it): 4, 5, 9, 14, 23, 37, 60, 97, 157, 254. What is 11 × the 7th number?
  29. 29.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?
  30. 30.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?
  31. 31.A leapfrog list starts 2, 7 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): 7, 3, 10, 13, 23, 36, 59, 95, 154, 249. What is 11 × the 7th number?
  33. 33.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  34. 34.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  35. 35.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  36. 36.A leapfrog list starts 3, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  38. 38.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?
  39. 39.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?
  40. 40.A leapfrog list starts 9, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?

Answer key

  1. 550
  2. 935
  3. 341
  4. 539
  5. 1122
  6. 759
  7. 825
  8. 814
  9. 759
  10. 803
  11. 803
  12. 891
  13. 704
  14. 407
  15. 671
  16. 572
  17. 869
  18. 517
  19. 1111
  20. 561
  21. 286
  22. 396
  23. 143
  24. 968
  25. 418
  26. 451
  27. 847
  28. 660
  29. 561
  30. 616
  31. 726
  32. 649
  33. 913
  34. 429
  35. 858
  36. 781
  37. 473
  38. 451
  39. 1067
  40. 847

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