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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 640 · 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, 3 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): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  3. 3.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?
  4. 4.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?
  5. 5.A leapfrog list starts 6, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.A leapfrog list starts 1, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  8. 8.Leapfrog list (each number is the sum of the two before it): 7, 8, 15, 23, 38, 61, 99, 160, 259, 419. What is 11 × the 7th number?
  9. 9.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?
  10. 10.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  11. 11.Leapfrog list (each number is the sum of the two before it): 2, 1, 3, 4, 7, 11, 18, 29, 47, 76. What is 11 × the 7th number?
  12. 12.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  13. 13.Leapfrog list (each number is the sum of the two before it): 8, 7, 15, 22, 37, 59, 96, 155, 251, 406. What is 11 × the 7th number?
  14. 14.A leapfrog list starts 8, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  16. 16.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?
  17. 17.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  18. 18.Leapfrog list (each number is the sum of the two before it): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  19. 19.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?
  20. 20.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?
  21. 21.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  22. 22.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  23. 23.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?
  24. 24.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  25. 25.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  26. 26.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  27. 27.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?
  28. 28.Leapfrog list (each number is the sum of the two before it): 6, 3, 9, 12, 21, 33, 54, 87, 141, 228. What is 11 × the 7th number?
  29. 29.Leapfrog list (each number is the sum of the two before it): 9, 2, 11, 13, 24, 37, 61, 98, 159, 257. What is 11 × the 7th number?
  30. 30.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?
  31. 31.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?
  32. 32.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?
  33. 33.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?
  34. 34.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?
  35. 35.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?
  36. 36.A leapfrog list starts 4, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  38. 38.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =
  39. 39.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  40. 40.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =

Answer key

  1. 319
  2. 143
  3. 1177
  4. 814
  5. 506
  6. 407
  7. 231
  8. 1089
  9. 341
  10. 847
  11. 198
  12. 1232
  13. 1056
  14. 880
  15. 286
  16. 1122
  17. 869
  18. 858
  19. 649
  20. 550
  21. 671
  22. 891
  23. 671
  24. 528
  25. 550
  26. 1034
  27. 693
  28. 594
  29. 671
  30. 231
  31. 451
  32. 572
  33. 792
  34. 495
  35. 1199
  36. 396
  37. 1177
  38. 1001
  39. 462
  40. 583

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