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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 885 · 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 1, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  3. 3.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?
  4. 4.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  5. 5.A leapfrog list starts 3, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  7. 7.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  8. 8.Leapfrog list (each number is the sum of the two before it): 4, 2, 6, 8, 14, 22, 36, 58, 94, 152. What is 11 × the 7th number?
  9. 9.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?
  10. 10.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  11. 11.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?
  12. 12.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?
  13. 13.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  14. 14.Leapfrog list (each number is the sum of the two before it): 7, 9, 16, 25, 41, 66, 107, 173, 280, 453. What is 11 × the 7th number?
  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): 5, 4, 9, 13, 22, 35, 57, 92, 149, 241. What is 11 × the 7th number?
  17. 17.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?
  18. 18.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  19. 19.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?
  20. 20.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  21. 21.Leapfrog list (each number is the sum of the two before it): 1, 9, 10, 19, 29, 48, 77, 125, 202, 327. What is 11 × the 7th number?
  22. 22.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  23. 23.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  24. 24.Leapfrog list (each number is the sum of the two before it): 1, 7, 8, 15, 23, 38, 61, 99, 160, 259. What is 11 × the 7th number?
  25. 25.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  26. 26.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?
  27. 27.A leapfrog list starts 8, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.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?
  29. 29.A leapfrog list starts 9, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  31. 31.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  32. 32.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  33. 33.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?
  34. 34.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  35. 35.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?
  36. 36.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?
  37. 37.Leapfrog list (each number is the sum of the two before it): 5, 1, 6, 7, 13, 20, 33, 53, 86, 139. What is 11 × the 7th number?
  38. 38.Leapfrog list (each number is the sum of the two before it): 2, 8, 10, 18, 28, 46, 74, 120, 194, 314. What is 11 × the 7th number?
  39. 39.Leapfrog list (each number is the sum of the two before it): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?
  40. 40.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =

Answer key

  1. 495
  2. 198
  3. 341
  4. 231
  5. 781
  6. 308
  7. 1001
  8. 396
  9. 616
  10. 484
  11. 858
  12. 231
  13. 693
  14. 1177
  15. 737
  16. 627
  17. 550
  18. 880
  19. 616
  20. 737
  21. 847
  22. 880
  23. 638
  24. 671
  25. 539
  26. 572
  27. 1056
  28. 319
  29. 1023
  30. 704
  31. 550
  32. 616
  33. 957
  34. 286
  35. 286
  36. 781
  37. 363
  38. 814
  39. 693
  40. 1122

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