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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 597 · 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): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 1, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?
  3. 3.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?
  4. 4.A leapfrog list starts 8, 5 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 1, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.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?
  7. 7.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  8. 8.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  9. 9.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  10. 10.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  11. 11.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  12. 12.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?
  13. 13.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  14. 14.A leapfrog list starts 1, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  16. 16.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  17. 17.A leapfrog list starts 8, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  18. 18.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  19. 19.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  20. 20.Leapfrog list (each number is the sum of the two before it): 4, 9, 13, 22, 35, 57, 92, 149, 241, 390. What is 11 × the 7th number?
  21. 21.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?
  22. 22.A leapfrog list starts 6, 8 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): 4, 6, 10, 16, 26, 42, 68, 110, 178, 288. What is 11 × the 7th number?
  24. 24.A leapfrog list starts 2, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  26. 26.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  27. 27.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  28. 28.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?
  29. 29.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  30. 30.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?
  31. 31.A leapfrog list starts 5, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  33. 33.A leapfrog list starts 4, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  35. 35.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  36. 36.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?
  37. 37.Leapfrog list (each number is the sum of the two before it): 4, 3, 7, 10, 17, 27, 44, 71, 115, 186. What is 11 × the 7th number?
  38. 38.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  39. 39.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  40. 40.A leapfrog list starts 2, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?

Answer key

  1. 341
  2. 407
  3. 1111
  4. 880
  5. 407
  6. 759
  7. 451
  8. 726
  9. 308
  10. 407
  11. 319
  12. 649
  13. 418
  14. 231
  15. 517
  16. 539
  17. 1232
  18. 627
  19. 429
  20. 1012
  21. 935
  22. 1034
  23. 748
  24. 462
  25. 462
  26. 693
  27. 1199
  28. 803
  29. 671
  30. 946
  31. 979
  32. 737
  33. 836
  34. 704
  35. 902
  36. 726
  37. 484
  38. 539
  39. 759
  40. 286

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