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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 576 · 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.A leapfrog list starts 8, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.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?
  3. 3.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  4. 4.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?
  5. 5.Leapfrog list (each number is the sum of the two before it): 9, 3, 12, 15, 27, 42, 69, 111, 180, 291. What is 11 × the 7th number?
  6. 6.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  7. 7.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?
  8. 8.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?
  9. 9.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?
  10. 10.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  11. 11.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  12. 12.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?
  13. 13.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  14. 14.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  15. 15.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  16. 16.Leapfrog list (each number is the sum of the two before it): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  17. 17.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  18. 18.A leapfrog list starts 7, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.Leapfrog list (each number is the sum of the two before it): 1, 6, 7, 13, 20, 33, 53, 86, 139, 225. What is 11 × the 7th number?
  20. 20.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?
  21. 21.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  22. 22.Leapfrog list (each number is the sum of the two before it): 9, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?
  23. 23.A leapfrog list starts 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.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?
  25. 25.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?
  26. 26.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  28. 28.A leapfrog list starts 4, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  30. 30.Leapfrog list (each number is the sum of the two before it): 6, 9, 15, 24, 39, 63, 102, 165, 267, 432. What is 11 × the 7th number?
  31. 31.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  32. 32.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?
  33. 33.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  34. 34.A leapfrog list starts 7, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.A leapfrog list starts 7, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.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?
  37. 37.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?
  38. 38.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  39. 39.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?
  40. 40.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?

Answer key

  1. 792
  2. 847
  3. 451
  4. 572
  5. 759
  6. 1177
  7. 231
  8. 561
  9. 429
  10. 1144
  11. 473
  12. 1111
  13. 363
  14. 1056
  15. 913
  16. 550
  17. 671
  18. 1177
  19. 583
  20. 462
  21. 1122
  22. 1023
  23. 528
  24. 286
  25. 539
  26. 1199
  27. 770
  28. 572
  29. 561
  30. 1122
  31. 759
  32. 1287
  33. 539
  34. 649
  35. 1001
  36. 671
  37. 286
  38. 737
  39. 803
  40. 803

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