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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 910 · 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): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?
  2. 2.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?
  3. 3.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  4. 4.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?
  5. 5.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?
  6. 6.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?
  7. 7.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?
  8. 8.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?
  9. 9.A leapfrog list starts 2, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  11. 11.A leapfrog list starts 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  13. 13.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  14. 14.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?
  15. 15.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  16. 16.Leapfrog list (each number is the sum of the two before it): 9, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?
  17. 17.Leapfrog list (each number is the sum of the two before it): 7, 1, 8, 9, 17, 26, 43, 69, 112, 181. What is 11 × the 7th number?
  18. 18.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  19. 19.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  20. 20.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  21. 21.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.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?
  23. 23.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?
  24. 24.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?
  25. 25.Leapfrog list (each number is the sum of the two before it): 3, 1, 4, 5, 9, 14, 23, 37, 60, 97. What is 11 × the 7th number?
  26. 26.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 9, 4, 13, 17, 30, 47, 77, 124, 201, 325. What is 11 × the 7th number?
  28. 28.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?
  29. 29.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  30. 30.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?
  31. 31.A leapfrog list starts 6, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.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?
  33. 33.A leapfrog list starts 7, 1 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): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?
  35. 35.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?
  36. 36.A leapfrog list starts 4, 7 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 1, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  39. 39.Leapfrog list (each number is the sum of the two before it): 8, 6, 14, 20, 34, 54, 88, 142, 230, 372. What is 11 × the 7th number?
  40. 40.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =

Answer key

  1. 704
  2. 858
  3. 605
  4. 594
  5. 1199
  6. 803
  7. 517
  8. 396
  9. 726
  10. 649
  11. 561
  12. 572
  13. 594
  14. 737
  15. 374
  16. 1023
  17. 473
  18. 924
  19. 1177
  20. 143
  21. 759
  22. 616
  23. 198
  24. 671
  25. 253
  26. 979
  27. 847
  28. 231
  29. 473
  30. 528
  31. 1034
  32. 506
  33. 473
  34. 418
  35. 957
  36. 836
  37. 583
  38. 231
  39. 968
  40. 1001

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