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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 857 · 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 3, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  3. 3.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?
  4. 4.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  5. 5.A leapfrog list starts 5, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  7. 7.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  8. 8.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  9. 9.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?
  10. 10.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  11. 11.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  12. 12.Leapfrog list (each number is the sum of the two before it): 4, 3, 7, 10, 17, 27, 44, 71, 115, 186. What is 11 × the 7th number?
  13. 13.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  14. 14.A leapfrog list starts 4, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.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?
  16. 16.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.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?
  18. 18.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?
  19. 19.Leapfrog list (each number is the sum of the two before it): 7, 5, 12, 17, 29, 46, 75, 121, 196, 317. What is 11 × the 7th number?
  20. 20.A leapfrog list starts 6, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  21. 21.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  22. 22.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?
  23. 23.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?
  24. 24.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  25. 25.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?
  26. 26.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?
  27. 27.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  28. 28.A leapfrog list starts 4, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.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?
  30. 30.A leapfrog list starts 2, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  32. 32.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?
  33. 33.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  34. 34.A leapfrog list starts 8, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.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?
  36. 36.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?
  37. 37.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  38. 38.2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 =
  39. 39.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  40. 40.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?

Answer key

  1. 605
  2. 737
  3. 814
  4. 539
  5. 715
  6. 693
  7. 638
  8. 627
  9. 880
  10. 583
  11. 671
  12. 484
  13. 968
  14. 308
  15. 396
  16. 1199
  17. 792
  18. 979
  19. 825
  20. 418
  21. 1023
  22. 946
  23. 396
  24. 792
  25. 550
  26. 495
  27. 374
  28. 748
  29. 1056
  30. 902
  31. 616
  32. 517
  33. 1034
  34. 1232
  35. 363
  36. 1177
  37. 759
  38. 462
  39. 231
  40. 231

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