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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 380 · 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, 4, 7, 11, 18, 29, 47, 76, 123, 199. What is 11 × the 7th number?
  2. 2.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  3. 3.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  4. 4.Leapfrog list (each number is the sum of the two before it): 4, 7, 11, 18, 29, 47, 76, 123, 199, 322. What is 11 × the 7th number?
  5. 5.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?
  6. 6.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  7. 7.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  8. 8.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  9. 9.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  10. 10.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?
  11. 11.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  13. 13.A leapfrog list starts 5, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  15. 15.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?
  16. 16.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  17. 17.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  18. 18.Leapfrog list (each number is the sum of the two before it): 1, 5, 6, 11, 17, 28, 45, 73, 118, 191. What is 11 × the 7th number?
  19. 19.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  20. 20.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  21. 21.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?
  22. 22.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  23. 23.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?
  24. 24.Leapfrog list (each number is the sum of the two before it): 3, 7, 10, 17, 27, 44, 71, 115, 186, 301. What is 11 × the 7th number?
  25. 25.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  26. 26.Leapfrog list (each number is the sum of the two before it): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?
  27. 27.A leapfrog list starts 6, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.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?
  29. 29.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  30. 30.A leapfrog list starts 1, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.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?
  32. 32.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  33. 33.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  34. 34.A leapfrog list starts 1, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  36. 36.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  37. 37.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  38. 38.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  39. 39.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?
  40. 40.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?

Answer key

  1. 517
  2. 286
  3. 1034
  4. 836
  5. 550
  6. 770
  7. 814
  8. 979
  9. 726
  10. 913
  11. 814
  12. 429
  13. 1067
  14. 341
  15. 792
  16. 1067
  17. 517
  18. 495
  19. 1023
  20. 627
  21. 616
  22. 253
  23. 451
  24. 781
  25. 825
  26. 704
  27. 946
  28. 957
  29. 759
  30. 319
  31. 649
  32. 616
  33. 1144
  34. 495
  35. 374
  36. 858
  37. 451
  38. 1001
  39. 1034
  40. 550

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