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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 123 · 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, 9, 12, 21, 33, 54, 87, 141, 228, 369. What is 11 × the 7th number?
  2. 2.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?
  3. 3.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  4. 4.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  5. 5.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?
  6. 6.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?
  7. 7.A leapfrog list starts 6, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  8. 8.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  9. 9.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?
  10. 10.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  11. 11.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  12. 12.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  13. 13.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?
  14. 14.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  15. 15.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?
  16. 16.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  17. 17.Leapfrog list (each number is the sum of the two before it): 7, 6, 13, 19, 32, 51, 83, 134, 217, 351. What is 11 × the 7th number?
  18. 18.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?
  19. 19.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  20. 20.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  21. 21.A leapfrog list starts 7, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  23. 23.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  24. 24.Leapfrog list (each number is the sum of the two before it): 5, 4, 9, 13, 22, 35, 57, 92, 149, 241. What is 11 × the 7th number?
  25. 25.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?
  26. 26.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  27. 27.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?
  28. 28.A leapfrog list starts 8, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  30. 30.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?
  31. 31.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  32. 32.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  33. 33.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  34. 34.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?
  35. 35.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?
  36. 36.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?
  37. 37.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?
  38. 38.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?
  39. 39.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  40. 40.Leapfrog list (each number is the sum of the two before it): 4, 8, 12, 20, 32, 52, 84, 136, 220, 356. What is 11 × the 7th number?

Answer key

  1. 957
  2. 979
  3. 253
  4. 924
  5. 462
  6. 286
  7. 858
  8. 759
  9. 869
  10. 550
  11. 836
  12. 583
  13. 484
  14. 583
  15. 1144
  16. 968
  17. 913
  18. 539
  19. 319
  20. 198
  21. 825
  22. 462
  23. 539
  24. 627
  25. 517
  26. 506
  27. 231
  28. 616
  29. 814
  30. 561
  31. 660
  32. 374
  33. 616
  34. 583
  35. 407
  36. 1199
  37. 539
  38. 528
  39. 231
  40. 924

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