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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 994 · 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 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  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.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?
  4. 4.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  5. 5.A leapfrog list starts 1, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  7. 7.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  8. 8.Leapfrog list (each number is the sum of the two before it): 5, 8, 13, 21, 34, 55, 89, 144, 233, 377. What is 11 × the 7th number?
  9. 9.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?
  10. 10.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?
  11. 11.Leapfrog list (each number is the sum of the two before it): 9, 8, 17, 25, 42, 67, 109, 176, 285, 461. What is 11 × the 7th number?
  12. 12.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  13. 13.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.A leapfrog list starts 3, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.Leapfrog list (each number is the sum of the two before it): 7, 4, 11, 15, 26, 41, 67, 108, 175, 283. What is 11 × the 7th number?
  16. 16.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?
  17. 17.A leapfrog list starts 2, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  18. 18.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  19. 19.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?
  20. 20.Leapfrog list (each number is the sum of the two before it): 6, 4, 10, 14, 24, 38, 62, 100, 162, 262. What is 11 × the 7th number?
  21. 21.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?
  22. 22.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  23. 23.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  24. 24.Leapfrog list (each number is the sum of the two before it): 2, 4, 6, 10, 16, 26, 42, 68, 110, 178. What is 11 × the 7th number?
  25. 25.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  26. 26.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  27. 27.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  28. 28.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  29. 29.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?
  30. 30.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  31. 31.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?
  32. 32.A leapfrog list starts 6, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.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?
  34. 34.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  35. 35.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  36. 36.A leapfrog list starts 7, 6 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, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  38. 38.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
  39. 39.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  40. 40.A leapfrog list starts 4, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?

Answer key

  1. 891
  2. 935
  3. 847
  4. 231
  5. 847
  6. 539
  7. 143
  8. 979
  9. 803
  10. 539
  11. 1199
  12. 748
  13. 341
  14. 869
  15. 737
  16. 869
  17. 638
  18. 869
  19. 1287
  20. 682
  21. 286
  22. 891
  23. 429
  24. 462
  25. 517
  26. 1067
  27. 759
  28. 1199
  29. 451
  30. 737
  31. 616
  32. 594
  33. 836
  34. 407
  35. 704
  36. 913
  37. 902
  38. 506
  39. 594
  40. 924

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