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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 368 · 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): 7, 8, 15, 23, 38, 61, 99, 160, 259, 419. What is 11 × the 7th number?
  2. 2.A leapfrog list starts 5, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.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?
  4. 4.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?
  5. 5.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?
  6. 6.A leapfrog list starts 3, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  8. 8.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?
  9. 9.A leapfrog list starts 2, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.Leapfrog list (each number is the sum of the two before it): 5, 7, 12, 19, 31, 50, 81, 131, 212, 343. What is 11 × the 7th number?
  11. 11.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?
  12. 12.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?
  13. 13.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  14. 14.A leapfrog list starts 3, 3 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 8, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  17. 17.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  18. 18.Leapfrog list (each number is the sum of the two before it): 9, 7, 16, 23, 39, 62, 101, 163, 264, 427. What is 11 × the 7th number?
  19. 19.Leapfrog list (each number is the sum of the two before it): 6, 8, 14, 22, 36, 58, 94, 152, 246, 398. What is 11 × the 7th number?
  20. 20.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  21. 21.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  22. 22.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  23. 23.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  24. 24.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  25. 25.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  26. 26.Leapfrog list (each number is the sum of the two before it): 8, 1, 9, 10, 19, 29, 48, 77, 125, 202. What is 11 × the 7th number?
  27. 27.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?
  28. 28.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
  29. 29.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  30. 30.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?
  31. 31.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?
  32. 32.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  33. 33.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?
  34. 34.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  35. 35.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?
  36. 36.A leapfrog list starts 7, 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 4, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.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?
  39. 39.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?
  40. 40.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?

Answer key

  1. 1089
  2. 451
  3. 847
  4. 605
  5. 891
  6. 517
  7. 1023
  8. 1023
  9. 462
  10. 891
  11. 473
  12. 594
  13. 198
  14. 429
  15. 880
  16. 495
  17. 407
  18. 1111
  19. 1034
  20. 836
  21. 803
  22. 880
  23. 1177
  24. 715
  25. 1232
  26. 528
  27. 286
  28. 1144
  29. 594
  30. 550
  31. 341
  32. 550
  33. 847
  34. 1111
  35. 946
  36. 1001
  37. 924
  38. 616
  39. 869
  40. 858

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